Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/19/12
AREA FORECAST DISCUSSION
NWS TUCSON AZ
915 PM MST THU AUG 16 2012
.SYNOPSIS...AMPLE MOISTURE WILL PROVIDE SCATTERED SHOWERS AND
THUNDERSTORMS INTO THE WEEKEND. BELOW NORMAL DAYTIME TEMPERATURES
WILL ALSO CONTINUE FRIDAY AND SATURDAY. THE DAILY CYCLE OF MAINLY
AFTERNOON AND EVENING THUNDERSTORMS WILL RETURN NEXT WEEK ALONG WITH
NEAR NORMAL DAYTIME TEMPERATURES.
&&
.DISCUSSION...SCATTERED SHOWERS AND THUNDERSTORMS ONGOING ACROSS NRN
GREENLEE/GRAHAM/NRN COCHISE COUNTIES. ISOLATED SHOWERS PRODUCING
VERY LIGHT RAIN WERE WEAKENING ACROSS WRN/CENTRAL PIMA COUNTY. IR
SATELLITE IMAGERY INDICATED CLOUD TOPS TO GENERALLY BE WARMING
ACROSS SE AZ DURING THE PAST 1-2 HOURS. HOWEVER...CLOUD TOPS WERE
COOLING NE OF TUCSON ACROSS NRN GREENLEE/GRAHAM COUNTIES.
BASED ON SATELLITE/RADAR TRENDS AS WELL AS THE 17/00Z NAM AND 17/00Z
RUC HRRR...HAVE OPTED FOR SCATTERED SHOWERS/TSTMS THE REST OF
TONIGHT ACROSS GREENLEE/GRAHAM/NRN COCHISE COUNTIES. SCATTERED
SHOWERS AND ISOLATED TSTMS EXPECTED TO OCCUR ELSEWHERE. THE LEAST
FAVORED AREA FOR PRECIP THE REST OF TONIGHT APPEARS TO BE ACROSS
WRN/CENTRAL PIMA COUNTY.
17/00Z RUC HRRR HAS BEEN CONSISTENT WITH PREVIOUS SOLUTIONS IN
DEVELOPING SHOWERS SHORTLY AFTER MIDNIGHT ACROSS THE TUCSON METRO
AREA. 17/00Z NAM HAS BEEN CONSISTENT WITH DEPICTING THE BEST CHANCE
OF PRECIP FRI TO OCCUR FROM TUCSON NWD/EWD WITH LESSER CHANCES OF
PRECIP SW OF TUCSON. LOCALLY HEAVY RAINFALL MAY OCCUR FRI AS STORM
MOTIONS ARE EXPECTED TO BE FAIRLY SLOW GIVEN LIGHT STEERING FLOW.
OTHERWISE...MOSTLY CLOUDY TO CLOUDY SKIES ON TAP THE REST OF TONIGHT
AND FRI. HIGH TEMPS FRI EXPECTED TO BE ABOUT 5-10 DEGS F OR SO BELOW
NORMAL.
&&
.PREV DISCUSSION...FOR FRIDAY INTO SATURDAY...STILL PLENTY OF
MOISTURE WITH HIGH PRESSURE PARKED TO OUR NORTH. THERE IS A
POTENTIAL FOR THESE TO BE VERY ACTIVE STORM DAYS...THOUGH THIS WILL
BE DEPENDENT AGAIN ON CLOUD COVER AND RESULTING DAYTIME HEATING.
MOISTURE VALUES WILL GRADUALLY TREND DOWN NEXT WEEK AS THE HIGH
PRESSURE ALOFT NUDGES SOUTHWARD. THIS WILL RESULT IN MORE OF A
STANDARD MONSOON PATTERN FORECAST. DAYTIME TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGH THE WEEKEND WITH NEAR NORMAL DAYTIME
TEMPERATURES NEXT WEEK.
&&
.AVIATION...SCT SHRA AND ISOLD -TSRA THE REST OF TONIGHT. SCT-NMRS
SHRA/TSRA FRIDAY AND FRIDAY EVENING. WIND GUSTS APPROACHING 40 KTS
WITH THE STRONGEST TSRA FRIDAY AFTERNOON. OTHERWISE...CLOUD DECKS
AROUND 8-12K FT AGL AND SURFACE WIND GENERALLY LESS THAN 10 KTS THRU
FRIDAY EVENING OR 18/06Z. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
&&
.FIRE WEATHER...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS AND BELOW
NORMAL DAYTIME TEMPERATURES THROUGH THE WEEKEND. THEREAFTER...
SCATTERED MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
WILL OCCUR EARLY NEXT WEEK.
&&
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE
&&
$$
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
840 PM EDT SAT AUG 18 2012
.UPDATE (TONIGHT - SUNDAY)...
00Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A CONTINUED HIGHLY
AMPLIFIED UPPER LEVEL PATTERN FOR AUGUST ACROSS THE CONUS. SHARP
RIDGING IS IN CONTROL OVER THE WESTERN THIRD OF THE NATION FOLLOWED
DOWNSTREAM BY A LARGE TROUGH COVERING MUCH OF THE CENTRAL/EASTERN
PORTION OF THE CONTINENT. OUR FORECAST AREA RESIDES BETWEEN THIS
TROUGH AND ANOTHER AREA OF UPPER LEVEL RIDGING OVER THE FL
STRAITS/CUBA. SHORTWAVE ENERGY THAT HELPED TO PROVIDE THE WET DAY
FOR MUCH OF THE REGION ON SATURDAY IS NOW SHEARING OUT TO THE
NORTHEAST AWAY FROM THE AREA. ANOTHER SERIES OF SHORTWAVE IMPULSES
WILL BE ROUNDING THE BASE OF THE TROUGH THROUGH MS/AL/GA OVERNIGHT
AND ARE HELPING TO TRIGGER QUITE A BIT OF CONVECTION OVER THE
NORTH-CENTRAL/NE GULF COAST THIS EVENING.
AT THE SURFACE...SUBTROPICAL RIDGE AXIS HAS NOT MOVED SIGNIFICANTLY
DURING THE PREVIOUS 24 HOURS WITH ITS AXIS ALIGNED THROUGH THE
FLORIDA STRAITS. THIS POSITION CONTINUES TO PROVIDE OUR AREA WITH A
MOIST SW/W FLOW IN THE LOWER LEVELS.
REST OF THE OVERNIGHT...AFTER ALL THE SHOWERS AND STORMS EARLIER
TODAY...THE EXIT OF THE SHORTWAVE TO OUR EAST AND RESULTING NVA HAS
COMBINED WITH LITTLE RESIDUAL INSTABILITY TO REALLY HELP QUIET THE
RADAR DOWN THIS EVENING. ONLY SEEING A FEW ISOLATED CELLS DOWN
TOWARD PUNTA GORDA AND FORT MYERS...AND APPEARS LIKELY THAT MOST
PLACES WILL SEE A DRY FORECAST THROUGH MUCH OF THE NIGHT. THE
SHORTWAVE ENERGY MOVING THROUGH THE LOWER MS VALLEY IS PROGGED TO
PASS FURTHER NORTH THAN ITS PREDECESSOR THIS MORNING. THIS PATH
SHOULD LIMIT THE SYNOPTIC SUPPORT FOR LIFT...AND HENCE NOT
ANTICIPATING TO SEE A REPEAT SUNDAY MORNING (IN TERMS OF
COVERAGE/DURATION/AMOUNTS) TO WHAT WE SAW ON SATURDAY. THAT BEING
SAID...THE LOW LEVEL FLOW PATTERN IS STILL FAVORABLE...EVEN IN THE
ABSENCE OF SYNOPTIC HELP...FOR LATE NIGHT SHOWERS AND STORMS OVER
THE COASTAL WATERS TO MIGRATE BACK TO THE COASTAL ZONES. WILL KEEP
ISOLATED SHOWERS IN THE FORECAST ALONG THE COAST...AND THEN INCREASE
COVERAGE TO SCATTERED 30% POPS FROM BRADENTON/SARASOTA NORTHWARD
ACROSS TAMPA BAY AFTER 09Z. FURTHER NORTH UP THE NATURE COAST...RAIN
CHANCES WILL BE EVEN HIGHER IN CLOSEST PROXIMITY TO THE PASSING
ENERGY...BUT FOR NOW WILL KEEP LIKELY/NUMEROUS WORDING OUT OF THE
GRIDS.
THE EXPECTATION OF MORE SOLAR INSOLATION ON SUNDAY SHOULD ALLOW THE
FORMATION OF A SEA-BREEZE BY EARLY AFTERNOON. THIS INLAND PUSH IS
ANTICIPATED TO TRANSITION THE BEST RAIN CHANCES INLAND FROM THE I-75
CORRIDOR BY LATE AFTERNOON.
&&
.PREVIOUS DISCUSSION (SUNDAY - MONDAY)...
THE PATTERN ALOFT CONTINUES NEARLY THE SAME WITH TROUGHING OVER THE
EASTERN STATES...WITH SHORT WAVE TROUGHS ROTATING THROUGH IT...AS
THE RIDGE REMAINS SOUTH OF THE STATE. THE SHORT WAVE TROUGHS WILL
DEEPEN THE LONG WAVE TROUGH EVER SO SLIGHTLY AND NUDGE THE SE U.S.
FRONTAL TROUGH/BOUNDARY INTO NORTHERN FL BY MON. MEANWHILE THE
SURFACE RIDGE AXIS RESIDES OVER SOUTHERN FL.
DEEP SW TO WESTERLY FLOW OVER THE AREA WILL KEEP THE ATMOSPHERE
VERY MOIST WITH PWAT VALUES AROUND 2 INCHES OR HIGHER. SHORT WAVE
TROUGH ENERGY TO THE NORTH...THE APPROACHING FRONTAL
TROUGH/BOUNDARY...AND SOUTHERLY TO SW LOW LEVEL FLOW/ ALTHOUGH
SHIFTING TO WESTERLY DURING AFTERNOON SEA BREEZES/ WILL RESULT IN
OVERNIGHT NIGHT/EARLY MORNING CONVECTION ON THE GULF THAT PUSHES
ONSHORE IN THE MORNING HOURS AND TRENDS DOWN AT IT SHIFTS EAST IN
THE AFTERNOON. WILL CONTINUE THE CURRENT POPS OF SCATTERED DURING
THE DAY AND ISOLATED IN THE EVENINGS...WITH THE HIGHEST ODDS IN THE
CENTRAL AND NORTH. THE FAR NORTH COULD SEE SOME LIKELY POPS MON AS
THE FRONT NEARS.
&&
.AVIATION...
MAINLY VFR THROUGH 06-08Z OR SO...THEN INCREASING SHOWERS AND/OR
STORMS DEVELOPING OVER THE GULF AND MOVING ONSHORE. MOST LIKELY
TERMINALS TO EXPERIENCE SHRA/TSRA WILL BE PIE AND TPA AGAIN...BUT DO
NOT EXPECT AS MUCH ACTIVITY AS THIS MORNING. CONFIDENCE IN COVERAGE
AND TIMING TOO LOW TO INCLUDE TEMPO MVFR/IFR CONDITIONS THIS FAR
OUT.
&&
.MARINE...
ATLANTIC HIGH PRESSURE WILL RIDGE ACROSS SOUTHERN FL WATERS THROUGH
TUE...AS A FRONTAL BOUNDARY SETTLES OVER THE NORTHERN WATERS MON.
THE BOUNDARY WEAKENS WED AND THU...ALLOWING THE RIDGE AXIS TO LIFT
NORTH...TO CENTRAL WATERS.
GENERALLY SOUTH TO SW WINDS BUT BECOMING WESTERLY IN AFTERNOON
SEA BREEZES. SPEEDS 5-1O KT ALTHOUGH NORTHERN WATERS WILL BE
AROUND 15 KT AS THE FRONT NEARS ON MON. MAIN MARINE HAZARDS WILL BE
ISOLATED TO SCATTERED THUNDERSTORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 76 90 78 91 / 20 40 20 40
FMY 76 92 76 93 / 20 30 20 40
GIF 74 92 75 92 / 20 50 20 50
SRQ 81 86 77 89 / 20 30 20 40
BKV 71 92 73 91 / 20 50 20 50
SPG 80 90 79 89 / 20 40 20 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
PREVIOUS DISCUSSION...RUDE
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
823 PM EDT Sat Aug 18 2012
.NEAR TERM...
[Through Tonight] The PoP forecast is tricky tonight as most of
the guidance does not appear to have a very good handle on the
large mass of rain with embedded thunderstorms approaching from
the west. The 18z NAM does not know that this rain exists, and
most of the hi-res guidance is struggling as well. The HRRR seems
to have a fair handle on the current rain area though and moves it
eastward overnight while gradually weakening. Although gradual
weakening is expected, it will likely move into at least the
western part of the forecast area overnight, so PoPs were raised
into the likely range (60-70 percent) roughly from the
Apalachicola river westward, with 30-50 percent PoPs east of
there. This is only round 1 of what may be several rounds of
showers with embedded thunderstorms over the next few days with a
tropical airmass in place and the base of a broad upper level
trough affecting the area.
$$
.SHORT TERM...
[Sunday through Monday night] Looks like a very unsettled period
with the broad trough over the eastern CONUS deepening as
several impulses drop southeastward from the plains into the base
of the trough. The axis of the trough will remain west of the
local region which will tap into the tropical moisture associated
with Helene or its remnants in the deep layer southwest flow. The
GFS continues to show the upper jet dipping well into the
southeastern states Sunday into Monday placing the Tri-State area
within the right entrance region. SPC`s day 2 discussion currently
mentions this put no highlighted area for a severe risk at this
time. This will need to be monitored closely. At the surface, a
cold front will approach from the northwest pushing into our
western zones Monday possibly becoming quasi-stationary late
Monday or Tuesday. As mentioned in an earlier discussion, this
could set the stage for a heavy rain event with localized
flooding. Understandably PoPs will be rather high during this
period and will generally go above numerical guidance. Max temps
will be held down a few degrees with the extensive cloud cover and
convective activity.
&&
.LONG TERM...
[Tuesday through Saturday] With the mean upper level trough
expected to remain quite persistent across the eastern half of the
U.S. through much (if not all) of the upcoming week, impulses of
energy rounding the base of the trough over the Southeast will
combine with plenty of deep layer moisture to keep above normal
PoPs in the fcst throughout much of the extended period.
Additionally, the likely remnants of Tropical Storm Helene (which
is still progged to move into southern Mexico, well away from our
region), may still play an important role in our fcst before the
week is over. While there are still plenty of discrepancies
between the global models (and run to run differences within each
model) over timing and potential moisture influx, the simple
presence of the steep upper level trough, will likely pull in some
deep layer tropical moisture into our region from the SW by mid to
late next week. Now, the latest runs of the GFS (00 UTC) and ECMWF
(12 UTC Thu), are back to showing some potential for a "break" in
the organized convection later on Tue. and possibly lasting into
Thu., but am not ready to buy into this solution just yet, given
the numerous changes and uncertainty surrounding Helene. Should
this become a trend that all of the global models begin embracing,
then PoPs can be adjusted downward at a later time. Also, with the
increased cloud cover which is still expected during the day, the
effects of the more typical afternoon sea breeze will be somewhat
limited (except for possibly Tue aftn thru Thu.), so high temps
should average a bit below climo values through much of the
period. While this does NOT appear to be the best stretch of
"beach weather" by any means, the potential of a good stretch of
widespread rainfall will certainly help many areas to continue to
chip away at our long term ongoing drought. Please stay tuned to
the latest fcsts from the National Weather Service, as this
pattern may need some fine tuning once the global models come into
better agreement with each other, and maintain more run to run
consistency.
&&
.AVIATION...
[Through 00z Monday] Latest radar trends show a large area of
showers and thunderstorms stretching from central Alabama into
the northern Gulf of Mexico, pushing steadily to the east. This
activity will begin to impact the western terminals (KDHN and
KECP) over the next few hours with SHRA and TSRA. Terminals
farther east may be impacted later tonight. Given these trends,
have increased mention of rain and thunder in the TAF`s throughout
the forecast period at all terminals.
&&
.MARINE...
Winds will be from the southwest at least through mid-week with
winds and seas gradually increasing to cautionary levels by Tuesday
as the pressure gradient tightens ahead of a cold front. This front
will also bring numerous showers and thunderstorms to the coastal
waters. Winds and seas may subside below headline criteria on
Wednesday.
&&
.FIRE WEATHER...
Typical of this wet summer pattern, afternoon relative humidities
will remain well above critical levels over the next several days
and, and therefore, conditions will continue to remain safely
above red flag levels.
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
Near Term...DVD
Short Term/Marine...Barry
Long Term...Gould
Aviation...Camp
Fire Wx...Block
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
407 AM EDT FRI AUG 17 2012
.DISCUSSION...
...FAVORABLE WINDS AND SEAS THIS WEEKEND BUT OFFSHORE MOVING STORMS
WILL REMAIN A CONCERN FOR BOATERS...
CURRENT...SURFACE RIDGE AXIS REMAINS NEAR LAKE OKEECHOBEE...ALTHOUGH
IT APPEARS TO HAVE SLIPPED TOWARD THE SOUTH END OF THE LAKE GIVEN
THE SW WINDS NOW IN PLACE AT KOBE AND SPGF1. HOWEVER...SFC METAR AND
PROFILER DATA DON`T SUGGEST THAT THE FLOW IS ANY MORE VEERED COMPARED
TO THE THIS TIME LAST NIGHT. A COUPLE OF SHOWERS/TS POPPED UP AFTER
MIDNIGHT IN A FEW POCKETS OF RESIDUAL INSTABILITY ACROSS THE NRN CWA
...NOT AT ALL SURPRISING IN THE SULTRY AUGUST AIR MASS. WATERVAPOR
IMAGERY AND RUC ANLYS FIELDS SHOW THE BASE OF THE BROAD ERN CONUS
MID/UPPER LEVEL TROUGH ACROSS SOUTH GA/NORTH FL...WITH A WELL-DEFINED
SHORT WAVE TROUGH EVIDENT OVER CTRL AL/GA DROPPING SEWD.
TODAY/TONIGHT...MODEL GUIDANCE IS SHOWING SOME STRENGTHENING OF THE
LOW TO MID LEVEL FLOW OVER THE PENINSULA TODAY...WITH THE 12KM NAM
A LITTLE MORE AGGRESSIVE TOWARD THIS END. WITH THE AFOREMENTIONED H50
SHORT WAVE DROPPING SOUTHWARD THIS SEEMS REASONABLE. PWATS WILL STAY
CLOSE TO 2.0" SO MOISTURE IS NO PROBLEM. WHILE THE ENHANCED LIFT
ASCD WITH THE VORT TO THE NORTH SHOULD PRODUCE ENHANCED LIFT THERE
IT IS ALSO PRODUCING A DECENT SWATH OF MID/UPPER DEBRIS CLOUDS AS
WELL. EXTENT OF MID/UPPER CLOUDINESS SNEAKING SOUTHWARD TOWARD OUR
NORTHERN ZONES EARLY THIS MORNING WILL BE SOMETHING TO KEEP TABS ON
AS IT COULD PROVIDE FOCUS FOR EARLY STORMS IN AREA OF DIFFERENTIAL
HEATING. MAINLY BECAUSE OF THE TROUGH TO THE NORTH...HAVE MADE TWEAK
TO BUMP POPS OVER NORTHERN COUNTIES TO 50 PCT TO MATCH FAVORED EAST
COASTAL AREAS. MAX TEMPS SHOULD AVERAGE ABOUT 1-3F ABOVE NORMAL.
EAST COASTAL COUNTIES AGAIN FAVORED SLIGHTLY FOR EVENING POPS (40 VS
30 REST OF CWA) GIVEN THE SLIGHT FASTER AND MORE VEERED WESTERLY
H85-H50 STEERING WINDS.
SATURDAY...UPPER TROUGHING OVER THE EASTERN CONUS WILL KEEP THE
ATLC RIDGE SUPPRESSED TO OUR SOUTH. THIS WILL MAINTAIN A STRONGER
OFFSHORE (W/SW) FLOW IN THE LOW AND MID LEVELS...DELAYING OR
PROHIBITING THE EAST COAST SEA BREEZE FROM FORMING AND ALLOWING
TEMPERATURES TO CLIMB A COUPLE DEGREES HIGHER AT THE COAST. THE
POSSIBLE LACK OF A SEA BREEZE BOUNDARY NORTH OF THE CAPE WOULD ACT
TO REDUCE COVERAGE AND INTENSITY OF STORMS IN VOLUSIA. BUT DO
EXPECT A SEA BREEZE TO FORM SOUTH OF THE CAPE WHICH SHOULD PROVIDE
A FOCUS FOR LATE AFTN/EARLY EVENING STORMS...SOME STRONG.
SUN-MON...ATLANTIC RIDGE IS FORECAST TO BUILD BACK A LITTLE BIT
ACROSS THE FL PENINSULA WHICH WILL REDUCE THE OFFSHORE FLOW AND
ALLOW THE SEA BREEZE TO FORM A LITTLE EARLIER. GFS SHOWS SOME
SLIGHT DRYING LIFTING NORTH ACROSS THE AREA ACCOMPANYING THE RIDGE
AXIS. THIS MAY DELAY ONSET OF STORMS A BIT BUT STEERING FLOW IS
FORECAST TO REMAIN OUT OF THE SW WHICH WILL FAVOR THE EAST SIDE OF
THE PENINSULA. SO WILL MAINTAIN SCATTERED STORM COVERAGE (AROUND
40 PERCENT).
TUE-THU...WILL MAINTAIN SCATTERED POPS BUT GFS SHOWS SOME MORE
SIGNIFICANT DRYING LIFTING NORTH INTO SOUTH FL WHICH COULD REDUCE
STORM COVERAGE ALONG THE TREASURE COAST WED AS DEEPER ONSHORE FLOW
DEVELOPS. DEEPER MOISTURE WILL CONTINUE TO EXIST ORLANDO NORTH
THU...WITH DRIER AIR SOUTH OF ORLANDO LIMITING RAIN CHANCES
SOMEWHAT.
&&
.AVIATION...
MADE SOME ADJUSTMENTS TO THE 06Z TAF PACKAGE TO SHOW A LITTLE
EARLIER TIMING FOR THE SERN AND NWRN AERODROMES (BEST CHANCE 18Z-
22Z) VERSUS THE CENTRAL SITES (20Z-23Z) AS HAS BEEN THE CASE FOR
MOST DAYS DURING THIS REGIME. IFR CIGS/VSBYS IN TS WITH G30KT OR
HIGHER IN SEVERAL STRONGER CELLS TODAY. STORM MOTION LOOKS TO BE
FROM ABOUT 270 AT A SOLID 12-17KT (15-20MPH).
&&
.MARINE...
SWAN HIGH BIAS CONTINUES TO PAINT SEA HGT FORECAST ABOUT 0.5 TO
1.0FT HIGHER THAN REALITY IN OFFSHORE FLOW REGIME. HAVE KEPT SEAS
1-2FT TODAY/EARLY TONIGHT WITH SLIGHT INCREASE WELL OFFSHORE AFTER
MIDNIGHT.
PERSISTENT TROFFING PATTERN OVER THE ERN CONUS WILL KEEP THE ATLC
RIDGE AXIS SUPPRESSED OVER THE S HALF OF THE FL PENINSULA INTO NEXT
WEEK. THIS WILL GENERATE LIGHT TO GENTLE W/SW FLOW...TURNING
ONSHORE EACH AFTN AS THE EAST COAST SEA BREEZE FORMS AND PUSHES
INLAND. THERE SHOULD BE GENTLE TO MODERATE NIGHTTIME BREEZE DUE
TO NOCTURNAL WIND ENHANCEMENT MAINLY OVER THE OPEN ATLC. SEAS 1-2FT
NEARSHORE AND 2-3FT OFFSHORE. PRIMARY CONCERN FOR BOATERS WILL BE
LATE AFTN/EARLY EVE STORMS MOVING OFFSHORE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 92 75 92 76 / 50 40 50 40
MCO 94 75 93 75 / 40 30 40 30
MLB 91 75 91 75 / 50 40 50 40
VRB 90 74 92 74 / 50 40 50 40
LEE 93 76 93 77 / 50 30 40 30
SFB 94 76 94 77 / 50 30 40 30
ORL 94 76 93 77 / 40 30 40 30
FPR 90 74 91 74 / 40 30 40 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...CRISTALDI
LONG TERM....KELLY
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1054 PM EDT SAT AUG 18 2012
.SYNOPSIS...
A FRONTAL SYSTEM WILL REMAIN NEAR THE FORECAST AREA THROUGH MONDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
TONIGHT...THE CONVECTIVE ACTIVITY HAS SHIFTED ON TO THE EAST.
INCLUDED A 60 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS SUMTER
AND CLARENDON COUNTIES UNTIL MIDNIGHT WITH A 20 PERCENT CHANCE
ELSEWHERE ALSO UNTIL MIDNIGHT. NOTHING CENTRAL AND WEST PORTIONS
RIGHT NOW BUT THERE ARE A FEW SHOWERS AND STORMS THAT MAY MOVE
IN FROM GEORGIA. AFTER MIDNIGHT...MAINLY NO MENTION OF CONVECTIVE
ACTIVITY BUT RUC13 AND NAM DO SHOW A WEAK SHORT WAVE APPROACHING
THE AREA BY 12Z SUNDAY MORNING. DON`T THINK THERE WILL BE ANYTHING
AROUND BUT DID INCREASE POPS TO 20 PERCENT BY 13Z. THINK THERE
WILL BE SOME STRATUS AND FOG...SO MENTIONED PATCHY FOG UNTIL 12Z.
OVERNIGHT LOW TEMPERATURES STILL IN THE UPPER 60S TO LOWER 70S.
SUNDAY...A STRONGER SHORT WAVE MOVES THROUGH. THE CHANCES FOR
SHOWERS AND THUNDERSTORMS INCREASE FROM 20 PERCENT IN THE MORNING
TO 50 PERCENT IN THE AFTERNOON. HIGH TEMPERATURES ARE HELD DOWN
INTO THE MIDDLE 50S DUE TO HIGHER POPS AND INCREASED CLOUD COVER.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
THE NAM AND GFS KEEP THE DIFFUSE FRONT AND HIGH MOISTURE IN THE
FORECAST AREA THROUGH MONDAY NIGHT. DEEPER MOISTURE WILL OCCUR AT
TIMES ASSOCIATED WITH A SERIES OF MID-LEVEL SHORTWAVE TROUGHS. THE
GUIDANCE POPS HAVE BEEN TRENDING UPWARD. HAVE FORECASTED POPS OF
50 TO 60 PERCENT WHICH MAY BE HIGH ENOUGH BECAUSE OF TIMING
UNCERTAINTY ASSOCIATED WITH THE SHORTWAVE TROUGHS. THE TEMPERATURE
GUIDANCE HAS BEEN CONSISTENT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
THE GFS AND ECMWF GENERALLY KEEP THE FRONT NEAR THE FORECAST AREA
DURING THE EXTENDED PERIOD. THE MODELS INDICATE UPPER-LEVEL
TROUGHING BUT ARE NOT IN GOOD AGREEMENT WITH THE TIMING OF A
SERIES OF SHORTWAVE TROUGHS AND ASSOCIATED DEEPER MOISTURE. THE
GFS ENSEMBLE GUIDANCE MEANS INDICATE CHANCE OR SLIGHT CHANCE POPS
THROUGH THE PERIOD. EXPECT TEMPERATURES A FEW DEGREES BELOW
CLIMATOLOGY BECAUSE OF THE EAST COAST TROUGHING. THE ENSEMBLE
MEANS SUPPORT LOWS IN THE MIDDLE TO UPPER 60S WITH HIGHS IN THE
MIDDLE TO UPPER 80S DURING THE PERIOD.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
SHOWERS AND A FEW STORMS HAVE EXITED TO THE EAST WITH A WEAK
SHORT WAVE. UNCERTAIN IF SKIES WILL BECOME MOSTLY CLEAR FOR
A SIGNIFICANT AMOUNT OF TIME BEFORE SUNRISE SUNDAY. BUT DECIDED
TO MVFR FOR VSBYS CAE AND CUB. WILL GO IFR AT AGS...DNL AND OGB
FOR MAINLY STRATUS CIGS WITH IFR VBSYS AT AGS AND OGB. EXPECT
THESE CONDITIONS TO PREVAIL 08Z-14Z. NOT CONFIDENT ENOUGH FOR
STRATUS CIGS EAST TAF SITES OF CAE AND CUB. AFTER 14Z MAINLY VFR
CONDITIONS BUT IFR-MVFR CONDITIONS ARE POSSIBLE IN AFTERNOON AND
EVENING CONVECTIVE ACTIVITY. DUE TO TIMING AND COVERAGE ISSUES DID
NOT INCLUDE IN TAF SITES.
EXTENDED AVIATION OUTLOOK...A CHANCE OF AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS...ALONG WITH A CHANCE OF LATE
NIGHT/EARLY MORNING RESTRICTIONS TO CIGS/VSBYS...AT TIMES THROUGH
THE PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
810 PM EDT SAT AUG 18 2012
.UPDATE...
NO SIGNIFICANT CHANGES SO FAR BUT PLANNING ON UPPING POPS OVERNIGHT.
RECENT HRRR RUNS AND 12Z AND 18Z GFS REALLY UPPING POTENTIAL FOR
OVERNIGHT SHRA/TSRA. HRRR TIMING ONSET AT ATL METRO ABOUT 06Z WITH
GFS A LITTLE LATER. OTHER MODELS INCLUDING LOCAL 4KM WRF AND NCEP
4KM WRF NMM NOT SO OPTIMISTIC ABOUT PRECIP. BEST H8 WAA ON GFS
PROGGED MORE OVER MIDDLE GA WITH SOME WAA AT HIGHER LEVELS FURTHER
NORTH.
SNELSON
&&
.PREV DISCUSSION... /ISSUED 321 PM EDT SAT AUG 18 2012/
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
EXPECT AN ACTIVE WEATHER PATTERN THROUGH THE SHORT TERM. SURFACE
ANALYSIS SHOWS A COLD FRONT NEAR A CARROLLTON TO ATLANTA TO ATHENS
LINE. EXPECT A STRONG UPPER DISTURBANCE OVER MS TO TRAVERSE THE AREA
AND SPARK ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND
SOUTH OF THE FRONT THROUGH MID EVENING. THIS ACTIVITY SHOULD
DIMINISH BY MIDNIGHT... BUT THE BREAK MAY BE SHORT LIVED AS A SERIES
OF DISTURBANCES BEGIN TO CARVE A LONG WAVE TROUGH ALONG THE LOWER MS
VALLEY REGION OVERNIGHT AND ON SUNDAY. AS A RESULT... EXPECT A VERY
ACTIVE SW FLOW ALOFT TO INTERACT WITH AN INCREASINGLY MOIST AND
UNSTABLE AIRMASS TO SPARK SCATTERED TO WIDESPREAD CONVECTION ACROSS
MUCH OF THE AREA STARTING EARLY ON SUNDAY AND CONTINUING THROUGH
MONDAY. THE GFS SHOWS A SURFACE LOW DEVELOPING ALONG THE STALLED
FRONT AND SWEEPING ACROSS THE STATE MONDAY NIGHT... WITH THE
TRAILING COLD FRONT FINALLY BRINGING SOME DRIER CONDITIONS TO AT
LEAST NORTH GA BY TUESDAY MORNING. AT THIS TIME...EXPECT THE
STRONGER STORMS TO OCCUR ON MONDAY AS THE UPPER TROUGH DEEPENS AND A
SURFACE LOW PUSHES INTO THE STATE DURING DAYTIME HEATING.
ALTHOUGH AMPLE CLOUD COVER AND WIDESPREAD SHOWERS SHOULD HELP
HINDER SEVERE STORM DEVELOPMENT ON SUNDAY AND MONDAY... THE
INCREASED FORCING EXPECTED ON MONDAY WARRANTS GREATER CONCERN FOR
MONDAY AFTERNOON AND EVENING. SPC DOES NOT HAVE THE FORECAST AREA
OUTLOOKED AT THIS TIME... BUT WILL MONITOR THIS POTENTIAL CLOSELY
GOING INTO MONDAY. OTHERWISE...LEANED TOWARD A MAV AND MET BLEND
FOR LOWS AND HIGHS THROUGH THE PERIOD WITH SOME UNCERTAINTY ON
TIMING AND COVERAGE OF CONVECTION AT THIS TIME.
39
LONG TERM /TUESDAY THROUGH SATURDAY/...
OVERALL GUIDANCE IN BETTER AGREEMENT THAN YESTERDAY WITH MAIN
INFLUENCING FEATURES FOR THE MAJORITY OF THE LONG TERM. THROUGH
TUESDAY BOTH THE GFS AND ECMWF KEEP THE MOISTURE FIELD SOUTH OF THE
NEARLY STATIONARY SFC FRONT ACROSS CENTRAL GEORGIA...WHICH
EVENTUALLY SAGS ACROSS SOUTHERN GEORGIA FOR WEDNESDAY INTO THURSDAY.
CURRENT POPS OF LOW END CHANCE IN THE SOUTH TO SLIGHT NORTHWARD
THROUGH THIS PERIOD SEEM REASONABLE. THE ECMWF HINTS AT A WEAK UPPER
LOW DRAWING MOISTURE IN A BIT FARTHER NORTHWARD THAN THE GFS ON
THURSDAY... BUT THERE IS DECENT UNCERTAINTY IN THIS SOLUTION THIS
FAR OUT SO WILL KEEP BEST CHANCE POPS IN SOUTH AND EAST PORTIONS.
WEAK SFC HIGH BUILDING INTO AREA NEAR END OF THE WEEK SHOULD LIMIT
CONVECTIVE DEVELOPMENT SO WILL ALSO CONTINUE THE CURRENT SLIGHT POPS
FOR THAT TIMEFRAME. NO SIGNIFICANT CHANGES NEEDED TO THE FORECAST
TEMPS AS LATEST MEX GUIDANCE KEEPING BETTER CONSISTENCY BETWEEN RUNS
THAN YESTERDAY. WITH ALL CONSIDERED...FORECAST LOOKS TO BE ON TRACK.
PREVIOUS DISCUSSION FOLLOWS...
03
PREVIOUS DISCUSSION ISSUED AT 426 AM EDT SAT AUG 18 2012/...
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
CWA REMAINS UNDER THE INFLUENCE OF A LONGWAVE TROUGH AT THE
BEGINNING OF THE LONG TERM. LATEST GUIDANCE STILL BRINGS A WAVE
ACROSS THE CWA NEAR THE BEGINNING OF THE LONG TERM BUT ABOUT 12
HOURS EARLIER THAN SUGGESTED YESTERDAY WITH MODELS SHOWING SUNDAY
NIGHT NOW. ALTHOUGH NAM/GFS/ECMWF/SREF SHOW SOME REFLECTION OF A
SFC LOW ASSOCIATED WITH THIS DISTURBANCE...THE GFS IS BY FAR THE
STRONGEST AND APPEARS TO BE OVERDONE ON STRENGTH AND PRECIP. AT
LEAST THROUGH MONDAY...LEANED TOWARD THE NAM/ECMWF SOLUTION TO
ACCOUNT FOR THE OVERDONE GFS. MAIN IMPACT WAS TO POPS THAT ARE IN
THE SLIGHT CHANCE TO LIKELY CATEGORY THROUGH MONDAY AS OPPOSED TO
THE LIKELY AND CATEGORICAL POPS SUGGESTED BY THE GFS. AFTER THE
INFLUENCES FROM THE WAVE ON MONDAY MOVES OUT OF THE CWA...RAIN
CHANCES DECREASE. BEST MOISTURE REMAINS ACROSS SOUTHERN HALF OF
CWA SO HAVE CONTINUED TO SHOW BEST POPS ACROSS THAT AREA. BY
MIDWEEK...LONGWAVE TROUGH CONTINUES TO BREAK DOWN ACROSS THE AREA
AND BEST MOISTURE CONTINUES TO SHIFT OFF TO THE EAST AS HIGH
PRESSURE PUSHES INTO THE CWA AT THE SFC. THIS WILL HELP TO LIMIT
POPS TO SLIGHT CHANCE ACROSS THE NORTH AND CHANCE ACROSS THE
SOUTHERN HALF OF THE CWA.
MEX MAX TEMPS ARE SLIGHTLY HIGHER THAN PREVIOUS RUN. LIKE THIS TREND
AND HAVE EVEN NUDGED MAX TEMPS UP A DEGREE IN SOME PLACES. MIN TEMPS
APPEAR A LITTLE COOL DURING THE WORK WEEK...SO HAD TO MAKE SOME
ADJUSTMENTS UPWARD HERE TOO.
11
AVIATION...
18Z UPDATE...
VFR CONDITIONS CURRENTLY OVER ALL TAF SITES AND EXPECTED TO PREVAIL
THROUGH THE TAF PERIOD. A COLD FRONT REMAINS NEARLY STATIONARY
ACROSS THE ATLANTA METRO AREA... AND WITH AN ACTIVE WESTERLY FLOW
ALOFT...EXPECT ANOTHER ROUND OF SCATTERED CONVECTION BY LATE
AFTERNOON-EARLY EVENING. LATEST HRRR MODEL INDICATES CONVECTION WILL
FIRE NEAR THE FRONT AND BRUSH THE ATLANTA AREA TAF SITES BY
21-23Z...BUT KEEPS THE MAIN CONVECTION JUST SOUTH OF ATL. WILL PLAY
IT SAFE AND CONTINUE TO SHOW TEMPO -TSRA 21-24Z FOR ALL TAF SITES
TODAY. MODELS AGREE ON WIDESPREAD CONVECTION MOVING IN LATE TONIGHT
AND PREVAILING ON SUNDAY. WILL SHOW VCSH BY 09Z...AND PREVAILING
-SHRA BY 12Z WITH PROB30 -TSRA 12-19Z SUN FOR NOW. WINDS WILL REMAIN
MAINLY WESTERLY AT 8KTS OR LESS.
//ATL CONFIDENCE...
18Z UPDATE...
MODERATE CONFIDENCE ON CONVECTION AND TIMING. HIGH CONFIDENCE ON
ALL OTHER ELEMENTS.
39
&&
.AVIATION...
00Z UPDATE...
PRIMARY CONCERN IS LIKELIHOOD AND TIMING OF SHRA/TSRA OVERNIGHT
AND SUNDAY. ONGOING TSRA CONTINUES TO DIMINISH. SHOULD SEE SCT SHRA
TIL 02Z. SOME CONSENSUS NOW THAT WIDESPREAD SHRA WITH SOME TSRA
WILL MOVE ACROSS MUCH OF AREA BETWEEN 06Z AND 12Z. HAVE CONTINUED
PREVAILING SHRA WITH TEMPO FOR TSRA IN FCST FOR THIS TIME FRAME.
WILL LIKELY SEE ANOTHER ROUND OF PRECIP SUNDAY AFTERNOON BUT WILL
DEPEND ON EVOLUTION OF MORNING PRECIP. FOR NOW KEEPING PROB30 FOR
19-23Z. WINDS SHOULD REMAIN REMAIN ON WEST COMPONENT WITH LIGHT
SPEEDS AS MORNING CLOUDS AND PRECIP LIMIT VERTICAL MIXING. CIGS
MAY DROP TO NEAR IFR IN PRECIP OVERNIGHT.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE IN SHRA/TSRA TIMING AND CIGS.
HIGH CONFIDENCE IN ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 68 86 68 84 / 30 50 60 60
ATLANTA 69 86 69 83 / 30 60 60 60
BLAIRSVILLE 62 80 66 80 / 20 30 50 50
CARTERSVILLE 68 85 67 84 / 30 50 60 60
COLUMBUS 72 87 70 84 / 30 60 70 70
GAINESVILLE 68 85 68 83 / 30 50 60 60
MACON 71 88 70 86 / 30 60 70 70
ROME 69 87 68 85 / 30 40 50 60
PEACHTREE CITY 68 86 67 84 / 30 60 60 60
VIDALIA 72 89 72 85 / 30 60 70 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....01
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
503 PM EDT FRI AUG 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE INTO THE FORECAST AREA TONIGHT
AND STALL. THE FRONT WILL REMAIN NEAR THE AREA THROUGH MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LATE THIS AFTERNOON...
SHOWERS AND THUNDERSTORMS HAVE INCREASED OVER THE AREA AHEAD OF
AN ADVANCING COLD FRONT. SOME STORMS HAVE BECOME SEVERE. MSAS
CAPES WERE 2000-3000 J/KG WHILE LIS WERE -6. WITH AFTERNOON
TEMPERATURES IN THE UPPER 80S TO LOWER 90S...LOW LEVEL LAPSE RATES
WERE STRONG. AS THE SUN BEGINS TO GO DOWN...THE SURFACE HEATING
WILL DECREASE AND THE ATMOSPHERE WILL BE NOT AS UNSTABLE.
THEREFORE...THE STORMS WILL NOT BE AS STRONG BY EVENING.
TONIGHT...
A FURTHER INCREASE IN MOISTURE AND CONVERGENCE AHEAD OF THE FRONT
SHOULD SUPPORT GREATER THUNDERSTORM COVERAGE TONIGHT UNLESS
WIDESPREAD CONVECTION DEVELOPS DURING THE LATE AFTERNOON RELEASING
MUCH OF THE INSTABILITY. THE LATEST HIGH-RESOLUTION WRF SHOWS THE
GREATEST COVERAGE DURING THE 800 PM TO 1000 PM TIME FRAME. THIS
MAY BE CORRECT BECAUSE BOTH THE NAM AND GFS PLUS RAP SHOW A MID-
LEVEL SHORTWAVE TROUGH MOVING INTO THE AREA DURING THE EVENING.
THUNDERSTORMS MAY CONTINUE OVERNIGHT BUT THE CHANCE SHOULD
DIMINISH BECAUSE OF DIURNAL COOLING AND PREVIOUS CONVECTION. THE
TEMPERATURE GUIDANCE TONIGHT MAY BE A LITTLE TOO COOL BECAUSE OF
CLOUDINESS AND MIXING ASSOCIATED WITH THE FRONT.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
THE NAM AND GFS KEEP THE SURFACE FRONT IN THE FORECAST AREA THOUGH
SUNDAY. CONVERGENCE ASSOCIATED WITH THE FRONT SUPPORT THUNDERSTORMS.
THE MODELS SHOW MOISTURE BECOMING SOMEWHAT SHALLOW BEHIND A LEAD
MID-LEVEL SHORTWAVE TROUGH TONIGHT. THE NAM AND GFS MOS ARE
CONSISTENT WITH CHANCE POP SATURDAY THROUGH SUNDAY. THE NAM MOS
INDICATED COOLER HIGH TEMPERATURES COMPARED THE GFS MOS. BOTH THE
NAM AND GFS SHOWED H85 WESTERLY FLOW SO EXPECT BREAKS IN THE
CLOUDINESS SUPPORTING WARMER TEMPERATURES. BELIEVE THE GUIDANCE
CONSENSUS IS THE BEST FORECAST AT THIS TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
THE GFS AND ECMWF GENERALLY KEEP THE FRONT NEAR THE FORECAST AREA
DURING THE EXTENDED PERIOD. THE MODELS INDICATE UPPER-LEVEL
TROUGHING BUT ARE NOT IN GOOD AGREEMENT WITH THE TIMING AND
PLACEMENT OF THE TROUGH AND DEEPER MOISTURE. THE GFS ENSEMBLE
GUIDANCE INDICATES THE GREATER SHOWER CHANCE MONDAY THROUGH
WEDNESDAY WITH THE MEAN POPS AROUND 40 PERCENT. THE ENSEMBLE MEAN
POPS LOWER TO 20 TO 30 PERCENT THURSDAY AND FRIDAY. HOWEVER...THE
ECMWF INDICATES THE DEEPEST MOISTURE THURSDAY AND FRIDAY. LEANED
TOWARD THE ENSEMBLE MEANS FOR THE POP FORECAST.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
A WEAK SHORT WAVE IS MOVING EAST THROUGH THE AREA THIS AFTERNOON.
THIS ALONG WITH AN UNSTABLE ATMOSPHERE IS AIDING IN THE DEVELOPMENT
OF SHOWERS AND THUNDERSTORMS WITH SOME STRONG TO SEVERE THUNDERSTORMS.
MSAS CAPES WERE 2000-3000 J/KG WITH LIS -6. OUTSIDE OF CONVECTIVE
ACTIVITY...HAVE VFR CONDITIONS. BUT AS SHOWERS AND STORMS MOVE IN...
HAVE INCLUDED TEMPO GROUPS FOR 1-2 HOURS FOR THUNDERSTORMS WITH IFR
CONDITIONS. AS THE SUN GOES DOWN...THE SURFACE HEATING WILL LESSEN
AND THE AIRMASS WILL NOT BE AS UNSTABLE. SO THE THREAT OF STRONG
STORMS WILL DIMINISH AROUND 02Z-03Z. EXPECT MAINLY VFR CONDITIONS
OVERNIGHT AS DEBRIS CLOUDS FROM CONVECTIVE ACTIVITY EXPECTED TO
LINGER MUCH OF THE NIGHT.
EXTENDED AVIATION OUTLOOK...A CHANCE OF SHOWERS AND
THUNDERSTORMS...ALONG WITH A CHANCE OF LATE NIGHT/EARLY MORNING
RESTRICTIONS TO CIGS/VSBYS...AT TIMES THROUGH THE PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
218 PM EDT FRI AUG 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE INTO THE FORECAST AREA TONIGHT
AND STALL. THE FRONT WILL REMAIN NEAR THE AREA THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THIS AFTERNOON...
A MOISTURE INCREASE AHEAD OF THE COLD FRONT HAS OCCURRED TODAY.
HEATING AND CONVERGENCE INTO THE PRE-FRONTAL TROUGH HAS RESULTED
IN SCATTERED THUNDERSTORMS THIS AFTERNOON. MODERATE INSTABILITY
AND A LARGE SURFACE TEMPERATURE-DEW POINT TEMPERATURE SPREAD
MAY HELP CAUSE DAMAGING WIND WITH A FEW OF THE THUNDERSTORMS.
TONIGHT...
A FURTHER INCREASE IN MOISTURE AND CONVERGENCE AHEAD OF THE FRONT
SHOULD SUPPORT GREATER THUNDERSTORM COVERAGE TONIGHT UNLESS
WIDESPREAD CONVECTION DEVELOPS DURING THE LATE AFTERNOON RELEASING
MUCH OF THE INSTABILITY. THE LATEST HIGH-RESOLUTION WRF SHOWS THE
GREATEST COVERAGE DURING THE 800 PM TO 1000 PM TIME FRAME. THIS
MAY BE CORRECT BECAUSE BOTH THE NAM AND GFS PLUS RAP SHOW A MID-
LEVEL SHORTWAVE TROUGH MOVING INTO THE AREA DURING THE EVENING.
THUNDERSTORMS MAY CONTINUE OVERNIGHT BUT THE CHANCE SHOULD
DIMINISH BECAUSE OF DIURNAL COOLING AND PREVIOUS CONVECTION. THE
TEMPERATURE GUIDANCE TONIGHT MAY BE A LITTLE TOO COOL BECAUSE OF
CLOUDINESS AND MIXING ASSOCIATED WITH THE FRONT.
&&
.SHORT TERM /SATURDAY/...
THE NAM AND GFS KEEP THE SURFACE FRONT IN THE FORECAST AREA THOUGH
SUNDAY. CONVERGENCE ASSOCIATED WITH THE FRONT SUPPORT THUNDERSTORMS.
THE MODELS SHOW MOISTURE BECOMING SOMEWHAT SHALLOW BEHIND A LEAD
MID-LEVEL SHORTWAVE TROUGH TONIGHT. THE NAM AND GFS MOS ARE
CONSISTENT WITH CHANCE POP SATURDAY THROUGH SUNDAY. THE NAM MOS
INDICATED COOLER HIGH TEMPERATURES COMPARED THE GFS MOS. BOTH THE
NAM AND GFS SHOWED H85 WESTERLY FLOW SO EXPECT BREAKS IN THE
CLOUDINESS SUPPORTING WARMER TEMPERATURES. BELIEVE THE GUIDANCE
CONSENSUS IS THE BEST FORECAST AT THIS TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE GFS AND ECMWF GENERALLY KEEP THE FRONT NEAR THE FORECAST AREA
DURING THE EXTENDED PERIOD. THE MODELS INDICATE UPPER-LEVEL
TROUGHING BUT ARE NOT IN GOOD AGREEMENT WITH THE TIMING AND
PLACEMENT OF THE TROUGH AND DEEPER MOISTURE. THE GFS ENSEMBLE
GUIDANCE INDICATES THE GREATER SHOWER CHANCE MONDAY THROUGH
WEDNESDAY WITH THE MEAN POPS AROUND 40 PERCENT. THE ENSEMBLE MEAN
POPS LOWER TO 20 TO 30 PERCENT THURSDAY AND FRIDAY. HOWEVER...THE
ECMWF INDICATES THE DEEPEST MOISTURE THURSDAY AND FRIDAY. LEANED
TOWARD THE ENSEMBLE MEANS FOR THE POP FORECAST.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
CU HAS DEVELOPED RAPIDLY...WITH RADAR NOW INDICATING ISOLATED
DEVELOPING CONVECTIVE ACTIVITY NEAR CAE/CUB. LATEST MODELS
INDICATE CHANCE OF ADDITIONAL CONVECTION DEVELOPING LATER THIS
AFTERNOON AND EVENING. WILL CONCENTRATE ON THE NEAR TERM AND
MONITOR RADAR TRENDS FOR TS/PRECIP INCLUSION IN THE TAFS. WILL NOT
INDICATE FOG/STRATUS LATE TONIGHT/EARLY SATURDAY AT THIS TIME DUE
TO UNCERTAINTIES WITH REGARD TO OVERNIGHT CLOUD COVER.
EXTENDED AVIATION OUTLOOK...A CHANCE OF SHOWERS AND
THUNDERSTORMS...ALONG WITH A CHANCE OF LATE NIGHT/EARLY MORNING
RESTRICTIONS TO CIGS/VSBYS...AT TIMES THROUGH THE PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1048 AM EDT FRI AUG 17 2012
.UPDATE...
DIFFICULT FORECAST FOR TODAY...WITH LITTLE FORECAST AGREEMENT WITH
THE SHORT TERM MODELS. OVERNIGHT MCS PUSHED INTO AL...WITH LARGE
AREA OF RAIN SHOWERS REMAINING ACROSS THE SOUTHERN HALF OF THE
STATE. THIS COMPLEX USHERED DECENT CLOUD COVER ACROSS THE FAR
WESTERN SIDE OF GA THIS MORNING...KEEPING A MORE STABILIZED
ENVIRONMENT OVER THAT AREA. CLOUDS ALREADY BEGINNING TO DIMINISH
THIS MORNING...BUT AS A RESULT OF THESE NOT WELL FORECAST
CLOUDS...MODELS HAVING DIFFICULTLY FINDING AN AGREEMENT ON
AFTERNOON ACTIVITY AS FRONTAL BOUNDARY APPROACHES THE REGION AND
STRONG UPPER LEVEL DISTURBANCE DROPS INTO THE STATE JUST AHEAD OF
IT. LOCAL WRF INDICATING A BUSY CONVECTIVE AFTERNOON FOR THE
STATE...WITH ISOLATED CELLS BECOMING MORE ORGANIZED AND LINEAR IN
NATURE BY LATE AFTERNOON AND EARLY EVENING AS THEY PUSH THROUGH
THE METRO AREA. BY CONTRAST...OTHER MODELS...SUCH AS THE
HRRR...KEEP MUCH OF THE ACTIVITY OVER FAR NORTH GEORGIA OR THE FAR
SE PORTIONS OF THE STATE...LEAVING THE METRO AREA LARGELY UNSCATHED.
FOR NOW...HAVE LEANED MORE TOWARDS THE THINKING OF SPC...WITH
ISOLATED STORMS EXPECTED THROUGH THE AFTERNOON AND INTO TONIGHT. THIS
THINKING IS MORE PARALLEL WITH THE LOCAL WRF SOLUTION. COULD SEE
SOME CONVECTIVE INITIATION AS EARLY AS 12-1PM...BUT EXPECTING
ACTIVITY TO REALLY FIRE 2-3PM AND AFTER.
AGAIN...THIS IS A DIFFICULT FORECAST...AND UPDATES WILL LIKELY BE
NECESSARY THROUGH THE DAY.
31
&&
.PREV DISCUSSION... /ISSUED 735 AM EDT FRI AUG 17 2012/
SHORT TERM /TODAY THROUGH SATURDAY/...
/ISSUED AT 401 AM EDT FRI AUG 17 2012/
THE CONVECTIVE REMNANTS OF AN MCS IS PUSHING ACROSS NORTH AL AND NW
GA EARLY THIS MORNING. EXPECT CURRENT WEAKENING TREND TO CONTINUE...
SPREADING MAINLY MID LEVEL CLOUDINESS AND SPOTTY LIGHT RAIN INTO THE
ATLANTA METRO AREA BY MID TO LATE MORNING. ALTHO CANNOT RULE OUT A
FEW RUMBLES OF THUNDER THIS MORNING... EXPECT SPOTTY LIGHT RAIN TO
BE THE MAIN PRECIP TYPE IN ATLANTA THIS MORNING.
THE GREATER CONCERN IS AN APPROACHING COLD FRONT THAT IS EXPECTED
TO PUSH INTO NORTH GEORGIA LATER THIS AFTERNOON. GFS AND NAM SHOW
A SERIES OF STRONG UPPER VORT MAXES TRAVERSING NORTH GEORGIA
DURING DAYTIME HEATING. THIS COUPLED WITH THE FRONT SHOULD RESULT
IN WIDESPREAD SHOWERS AND THUNDERSTORMS PUSHING INTO NORTH GEORGIA
TODAY...WITH SCATTERED CONVECTION POSSIBLY SPREADING INTO PARTS
OF CENTRAL GEORGIA AS WELL. RESIDUAL CLOUD COVER FROM THIS
MORNINGS DISSIPATING MCS SHOULD HELP HOLD TEMPERATURES AND
INSTABILITIES DOWN A BIT TODAY. HOWEVER...TIMING OF THE UPPER
VORT MAX DURING MAX HEATING...ALONG WITH FRONTAL FORCING...ALL
SUGGEST THE POTENTIAL FOR ISOLATED STRONG TO SEVERE STORMS ACROSS
PARTS OF NORTH GEORGIA LATER THIS AFTERNOON AND EARLY EVENING. SPC
CONTINUES TO PLACE MUCH OF NORTH GEORGIA IN A SLIGHT RISK AREA
TODAY...GENERALLY ALONG AND NORTH OF A LAGRANGE TO COVINGTON TO
ATHENS LINE. THE MAIN STORM THREATS WILL BE DAMAGING WIND AND
MARGINAL SIZED HAIL. LOCALLY HEAVY RAIN IS ALSO A CONCERN WITH
TRAINING CELLS AHEAD OF THE FRONT. THE UPPER DISTURBANCES PUSH
EAST BY MIDNIGHT...SO EXPECT THE ASSOCIATED CONVECTION AHEAD OF
THE FRONT TO GREATLY DIMINISH BY THEN...ESPECIALLY WITH LOSS OF
DAYTIME HEATING.
THE FRONT STALLS ACROSS CENTRAL GEORGIA ON SATURDAY...SO WILL
SHOW THE GREATER RAIN CHANCES THERE SATURDAY AFTERNOON. MARGINAL
INSTABILITIES AND LACK OF UPPER SUPPORT SHOULD HELP HOLD STORM
DEVELOPMENT BELOW SEVERE LIMITS ON SATURDAY.
OTHERWISE...STARTED WITH A MAV AND MET BLEND FOR TEMPS THROUGH THE
SHORT TERM...THEN LEANED TOWARD THE COOLER MET HIGHS FOR TODAY
WITH RESIDUAL CLOUDINESS...THEN WARMER MAV HIGHS ON SATURDAY WITH
LESS CLOUDS AND ONLY ISOLATED TO SCATTERED CONVECTION EXPECTED.
39
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
/ISSUED AT 401 AM EDT FRI AUG 17 2012/
CWA REMAINS IN LONGWAVE TROUGH AT THE BEGINNING OF THE LONG TERM.
MEANWHILE AT THE SFC...FRONT THAT MOVES THROUGH IN THE SHORT TERM
REMAINS SITUATED ACROSS THE SOUTHERN HALF OF THE STATE. THIS
PATTERN WILL DOMINATE THE LONG TERM. WITH FRONT MEANDERING AROUND
CENTRAL GEORGIA...BEST CHANCES OF RAIN THROUGH THE LONG TERM WILL
REMAIN ACROSS THE SOUTHERN HALF OF THE CWA. IN ADDITION WILL SEE
WEAK DISTURBANCES MOVE ALONG THE FRONT AS IT REMAINS STATIONARY.
GFS SHOWS THE BEST VORT MAX TO MOVE ALONG THE FRONT ON MONDAY AND
THIS WILL HELP TO REINFORCE CHANCE OF POPS. INITIALLY OVER THE
WEEKEND...POPS ARE ON THE LOWER SIDE OF GUIDANCE AS IT APPEARS MAV
IS OVER DOING POPS...WHEREAS LATER IN THE LONG TERM...POPS ARE
CLOSER TO GUIDANCE.
11
AVIATION...
12Z UPDATE...
TIMING TOOL AND HRRR MODEL INDICATES MID LEVEL CLOUDS AND SPOTTY
-SHRA MAY SPREAD INTO ATLANTA AREA FROM AL LATER THIS MORNING. WILL
SHOW BKN050 AND VCSH AT 16Z. THE GREATER CONVECTIVE THREAT WILL
BEGIN AT ATL AROUND 18Z AND CONTINUE THROUGH THE AFTERNOON- EARLY
EVENING HOURS WHEN A COLD FRONT PUSHES INTO FAR NORTH GA. EXPECT
CONVECTION TO GREATLY DIMINISH BY 04-06Z TONIGHT AS THE DRIVING
UPPER SHORT WAVE PUSHES EAST. WET GROUNDS SUGGEST POTENTIAL FOR IFR
CIGS BY 09-10Z SAT MORNING. EXPECT MAINLY WEST WINDS AROUND 8-10 KTS
BY MID-LATE MORNING...THEN WNW AT 5-7KTS LATER TONIGHT AS THE FRONT
DRAWS NEARER. ISOLATED SHOWERS MAY LINGER OVERNIGHT...BUT EXPECT THE
GREATER TSTM THREAT TO BE JUST SOUTH OF ATL ON SATURDAY.
//ATL CONFIDENCE...12Z UPDATE...
HIGH CONFIDENCE ALL ELEMENTS EXCEPT MEDIUM ON TIMING AND LOCATION OF
CONVECTION TODAY.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 87 69 89 67 / 80 40 30 20
ATLANTA 86 70 86 69 / 80 40 30 20
BLAIRSVILLE 80 66 81 62 / 80 50 20 10
CARTERSVILLE 86 69 85 64 / 90 50 20 20
COLUMBUS 91 72 89 70 / 80 40 30 20
GAINESVILLE 86 70 86 67 / 80 50 30 20
MACON 92 71 91 71 / 80 30 40 30
ROME 87 69 88 63 / 90 50 20 10
PEACHTREE CITY 87 69 86 66 / 80 40 30 20
VIDALIA 93 73 91 73 / 50 30 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....BAKER
AVIATION...31
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
401 AM EDT FRI AUG 17 2012
.SHORT TERM /TODAY THROUGH SATURDAY/...
THE CONVECTIVE REMNANTS OF AN MCS IS PUSHING ACROSS NORTH GA EARLY
THIS MORNING. EXPECT CURRENT WEAKENING TREND TO CONTINUE...SPREADING
MAINLY MID LEVEL CLOUDINESS AND SPOTTY LIGHT RAIN SHOWERS INTO THE
ATLANTA METRO AREA BY 5-6 AM THIS MORNING. ALTHO CANNOT RULE OUT A
FEW RUMBLES OF THUNDER THIS MORNING...EXPECT SPOTTY LIGHT RAIN TO
BE THE MAIN PRECIP TYPE IN ATLANTA THIS MORNING.
OF GREATER CONCERN IS AN APPROACHING COLD FRONT THAT IS EXPECTED
TO PUSH INTO NORTH GEORGIA LATER THIS AFTERNOON. GFS AND NAM SHOW
A SERIES OF STRONG UPPER VORT MAXES TRAVERSING NORTH GEORGIA
DURING DAYTIME HEATING. THIS COUPLED WITH THE FRONT SHOULD RESULT
IN WIDESPREAD SHOWERS AND THUNDERSTORMS PUSHING INTO NORTH GEORGIA
TODAY...WITH SCATTERED CONVECTION POSSIBLY SPREADING INTO PARTS
OF CENTRAL GEORGIA AS WELL. RESIDUAL CLOUD COVER FROM THIS
MORNINGS DISSIPATING MCS SHOULD HELP HOLD TEMPERATURES AND
INSTABILITIES DOWN A BIT TODAY. HOWEVER...TIMING OF THE UPPER
VORT MAX DURING MAX HEATING...ALONG WITH FRONTAL FORCING...ALL
SUGGEST THE POTENTIAL FOR ISOLATED STRONG TO SEVERE STORMS ACROSS
PARTS OF NORTH GEORGIA LATER THIS AFTERNOON AND EARLY EVENING. SPC
CONTINUES TO PLACE MUCH OF NORTH GEORGIA IN A SLIGHT RISK AREA
TODAY...GENERALLY ALONG AND NORTH OF A LAGRANGE TO COVINGTON TO
ATHENS LINE. THE MAIN STORM THREATS WILL BE DAMAGING WIND AND
MARGINAL SIZED HAIL. LOCALLY HEAVY RAIN IS ALSO A CONCERN WITH
TRAINING CELLS AHEAD OF THE FRONT. THE UPPER DISTURBANCES PUSH
EAST BY MIDNIGHT...SO EXPECT THE ASSOCIATED CONVECTION AHEAD OF
THE FRONT TO GREATLY DIMINISH BY THEN...ESPECIALLY WITH LOSS OF
DAYTIME HEATING.
THE FRONT STALLS ACROSS CENTRAL GEORGIA ON SATURDAY...SO WILL
SHOW THE GREATER RAIN CHANCES THERE SATURDAY AFTERNOON. MARGINAL
INSTABILITIES AND LACK OF UPPER SUPPORT SHOULD HELP HOLD STORM
DEVELOPMENT BELOW SEVERE LIMITS ON SATURDAY.
OTHERWISE...STARTED WITH A MAV AND MET BLEND FOR TEMPS THROUGH THE
SHORT TERM...THEN LEANED TOWARD THE COOLER MET HIGHS FOR TODAY
WITH RESIDUAL CLOUDINESS...THEN WARMER MAV HIGHS ON SATURDAY WITH
LESS CLOUDS AND ONLY ISOLATED TO SCATTERED CONVECTION EXPECTED.
39
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
CWA REMAINS IN LONGWAVE TROUGH AT THE BEGINNING OF THE LONG TERM.
MEANWHILE AT THE SFC...FRONT THAT MOVES THROUGH IN THE SHORT TERM
REMAINS SITUATED ACROSS THE SOUTHERN HALF OF THE STATE. THIS
PATTERN WILL DOMINATE THE LONG TERM. WITH FRONT MEANDERING AROUND
CENTRAL GEORGIA...BEST CHANCES OF RAIN THROUGH THE LONG TERM WILL
REMAIN ACROSS THE SOUTHERN HALF OF THE CWA. IN ADDITION WILL SEE
WEAK DISTURBANCES MOVE ALONG THE FRONT AS IT REMAINS STATIONARY.
GFS SHOWS THE BEST VORT MAX TO MOVE ALONG THE FRONT ON MONDAY AND
THIS WILL HELP TO REINFORCE CHANCE OF POPS. INITIALLY OVER THE
WEEKEND...POPS ARE ON THE LOWER SIDE OF GUIDANCE AS IT APPEARS MAV
IS OVER DOING POPS...WHEREAS LATER IN THE LONG TERM...POPS ARE
CLOSER TO GUIDANCE.
11
&&
.AVIATION...
06Z UPDATE...
VFR CONDITIONS EXPECTED TO PREVAIL. HOWEVER... A LINE OF ONGOING
CONVECTION IN TN WILL PUSH INTO NW GA BY 06-07Z...AND IF HOLDS
TOGETHER...COULD SPREAD AT LEAST MID LEVEL CIGS AND -SHRA`S INTO
THE ATLANTA METRO AREA AROUND 08-10Z THIS MORNING. EXPECT A
WEAKENING TREND TO CONTINUE AND HRRR MODEL INDICATES ONLY SPOTTY
-RA WILL MAKE IT INTO THE ATLANTA AREA... SO WILL SHOW VCSH AT
09-10Z FOR NOW. THE GREATER CONVECTIVE THREAT WILL BEGIN AT ATL
AROUND 16Z AND CONTINUE THROUGH THE AFTERNOON- EARLY EVENING HOURS
WHEN A COLD FRONT PUSHES INTO FAR NORTH GA. EXPECT CONVECTION TO
GREATLY DIMINISH BY 04-06Z TONIGHT AS THE DRIVING UPPER SHORT WAVE
PUSHES EAST. WET GROUNDS SUGGEST POTENTIAL FOR IFR CIGS BY 09-10Z
SAT MORNING. LIGHT WNW WINDS THIS MORNING WILL BE MORE WESTERLY 10
KTS OR LESS BY AFTN.
//ATL CONFIDENCE...06Z UPDATE...
HIGH CONFIDENCE ALL ELEMENTS EXCEPT MEDIUM ON TIMING AND LOCATION OF
CONVECTION TODAY.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 87 69 89 67 / 50 40 30 20
ATLANTA 86 70 86 69 / 70 40 30 20
BLAIRSVILLE 80 66 81 62 / 80 50 20 10
CARTERSVILLE 86 69 85 64 / 90 50 20 20
COLUMBUS 91 72 89 70 / 60 40 30 20
GAINESVILLE 86 70 86 67 / 70 50 30 20
MACON 92 71 91 71 / 40 30 40 30
ROME 87 69 88 63 / 90 50 20 10
PEACHTREE CITY 87 69 86 66 / 70 40 30 20
VIDALIA 93 73 91 73 / 40 30 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...39
LONG TERM....11
AVIATION...39
AREA FORECAST DISCUSSION...UPDATED FOR AVIATION
NWS PEACHTREE CITY GA
138 AM EDT FRI AUG 17 2012
.UPDATE...
/ISSUED AT 1020 PM EDT THU AUG 16 2012/
HAVE UPDATED FORECAST TO ADD SLIGHT CHANCE OF THUNDERSTORMS OVER
MUCH OF NORTH GEORGIA TONIGHT...NORTH OF AN ATLANTA TO ATHENS LINE
FOR NOW. THERE ARE A FEW STORMS DEVELOPING AHEAD OF THE MCS MOVING
THROUGH TENNESSEE AND KENTUCKY. WILL CONTINUE TO WATCH AND SEE HOW
THE CONVECTION DEVELOPS. NO OTHER CHANGES AT THIS TIME.
41
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
/ISSUED AT 317 PM EDT THU AUG 16 2012/
STATIONARY FRONT ACROSS CENTRAL GA WITH BEST INSTABILITY ACROSS THE
SOUTHERN COUNTIES. THAT IS WHERE THE BEST CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL BE INTO THE MID EVENING HOURS. A CONCERN TO WATCH
FOR IS SHORT WAVES IN THE UPPER FLOW COMING FROM MS/AL THAT COULD
AFFECT THE WESTERN CWA THIS EVENING.
THE MAIN CONCERN WILL THEN BE A COLD FRONT APPROACHING N GA FRIDAY
AFTERNOON. GFS/NAM THEN DIFFER HOW FAR TO TAKE THE FRONT INTO THE
AREA WITH THE GFS MOVING THE FRONT TO CENTRAL GA AT DAYS END FRIDAY
AND THE NAM MOVING THE FRONT INTO N GA. THINK THE NAM MOVEMENT IS
BETTER AND THE HIGHER POPS FROM THE NAM MOS MORE IN LINE THAN THE
LOWER GFS MOS POPS. A FLAIR UP OF SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED FRIDAY WITH THE APPROACH OF THE FRONT AND SPC HAS
HIGH-LIGHTED MAINLY N GA FOR A SLIGHT RISK OF SEVERE THUNDERSTORMS.
THIS IS PARTLY DUE TO A SHORT WAVE AIDING THE STORM DEVELOPMENT.
THE FRONT WILL LIKELY BECOME STATIONARY FRIDAY NIGHT ACROSS N GA.
WHILE SHOWER AND THUNDERSTORM ACTIVITY WILL DIMINISH...CHANCES WILL
REMAIN IN THE FORECAST ALL NIGHT.
FORECAST LOW TEMPERATURES RUNNING NEAR NORMAL TONIGHT AND FRIDAY
NIGHT. FORECAST HIGH TEMPERATURES RUNNING NEAR TO SLIGHTLY BELOW
NORMAL FOR FRIDAY AND WENT WITH THE COOLER MET MOS HIGHS. THESE
TEMPERATURES COULD BE TOO COOL FOR PORTIONS OF THE SE CWA.
OVERALL CONFIDENCE IS MEDIUM.
BDL
.LONG TERM /SATURDAY THROUGH THURSDAY/...
/ISSUED AT 317 PM EDT THU AUG 16 2012/
AFOREMENTIONED FRONT WILL BE WORKING ITS WAY THROUGH THE AREA
SATURDAY AND SUNDAY AS THE STRONG UPPER TROUGH DIGS INTO THE
EASTERN HALF OF THE COUNTRY. VARIOUS SHORTWAVES ROUNDING THE BASE
OF THE TROUGH ALONG WITH SOUTHWEST FLOW ALOFT AND TROPICAL
CONNECTION FROM THE TROPICAL WAVE OVER THE BAY OF CAMPECHE WILL
KEEP DIFFERENT WAVES OF CONVECTION IN THE AREA THROUGH THE
EXTENDED. 12Z GFS NO LONGER TRIES TO CUTOFF A SHORTWAVE MIDWEEK
WHEREAS THE ECMWF IS STILL DOING THIS. WITH THE CUTOFF...THE ECMWF
DEVELOPS A MORE PROGRESSIVE SYSTEM AND PUSHES THE TROUGH UP INTO
SOUTHEAST CANADA WITH RIDGING BUILDING INTO THE SOUTH...WHEREAS
THE GFS KEEPS THE TROUGH AS THE DOMINANT FEATURE...WHICH WILL
IMPACT WHICH DAYS NEXT WEEK HAVE PRECIP. GUIDANCE IS ALSO HINTING
AT A SLIGHTLY WARMER SOLUTION THIS TIME AROUND. WITH ALL THESE
CHANGES...ALBEIT MINOR...HAVE MADE NO CHANGES TO THE FORECAST
BEYOND 48 HOURS GIVEN THE UNCERTAINTY. SEE PREVIOUS DISCUSSION
BELOW.
TDP
&&
.AVIATION...
06Z UPDATE...
VFR CONDITIONS EXPECTED TO PREVAIL. HOWEVER... A LINE OF ONGOING
CONVECTION IN TN WILL PUSH INTO NW GA BY 06-07Z...AND IF HOLDS
TOGETHER...COULD SPREAD AT LEAST MID LEVEL CIGS AND -SHRA`S INTO THE
ATLANTA METRO AREA AROUND 08-10Z THIS MORNING. EXPECT A WEAKENING
TREND TO CONTINUE AND HRRR MODEL INDICATES ONLY SPOTTY -RA WILL MAKE
IT INTO THE ATLANTA AREA... SO WILL SHOW VCSH AT 09-10Z FOR NOW. THE
GREATER CONVECTIVE THREAT WILL BEGIN AT ATL AROUND 16Z AND CONTINUE
THROUGH THE AFTERNOON-EARLY EVENING HOURS WHEN A COLD FRONT PUSHES
INTO FAR NORTH GA. EXPECT CONVECTION TO GREATLY DIMINISH BY 04-06Z
TONIGHT AS THE DRIVING UPPER SHORT WAVE PUSHES EAST. WET GROUNDS
SUGGEST POTENTIAL FOR IFR CIGS BY 09-10Z SAT MORNING. LIGHT WNW
WINDS THIS MORNING WILL BE MORE WESTERLY 10 KTS OR LESS BY AFTN.
//ATL CONFIDENCE...06Z UPDATE...
HIGH CONFIDENCE ALL ELEMENTS EXCEPT MEDIUM ON TIMING AND LOCATION OF
CONVECTION TODAY.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 68 89 69 88 / 10 50 40 40
ATLANTA 72 87 71 86 / 10 70 40 40
BLAIRSVILLE 64 80 67 81 / 10 80 50 40
CARTERSVILLE 66 86 68 86 / 20 90 50 40
COLUMBUS 72 90 73 88 / 10 40 40 50
GAINESVILLE 69 86 70 85 / 10 70 40 40
MACON 72 91 71 90 / 10 50 30 50
ROME 68 87 69 87 / 20 90 60 40
PEACHTREE CITY 67 87 68 86 / 10 60 40 40
VIDALIA 73 94 73 92 / 20 30 20 50
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BDL/39
LONG TERM....TDP
AVIATION...39
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1035 AM CDT FRI AUG 17 2012
.DISCUSSION...
ISSUED 1029 AM CDT FRI AUG 17 2012
ONLY MINOR CHANGES TO GRIDS THIS MORNING.
HIGH PRESSURE OVER THE CENTRAL PLAINS CONTINUES TO BUILD INTO
ILLINOIS IN THE WAKE OF YESTERDAYS COLD FRONT. SCATTERED CU WILL
DEVELOP WITH COOL TEMPS AT MID-LEVELS AND RESIDUAL MOISTURE FROM
YESTERDAYS CONVECTION. OTHERWISE...CURRENT FORECAST IN THE MIDDLE
70S TO NEAR 80 FAR SOUTHEAST LOOKS REASONABLE BASED ON LATEST LAMP
AND THIS MORNINGS KILX SOUNDING.
BARKER
&&
.AVIATION...
ISSUED 633 AM CDT FRI AUG 17 2012
LATEST IR SATELLITE LOOP SHOWS THE WESTERN EDGE OF CLOUD BAND
SOUTH OF I-70 AT DAYBREAK. HIGH PRESSURE IN THE CENTRAL PLAINS
WILL DRIFT TOWARD THE MID MISSISSIPPI VALLEY AND BE IN CONTROL OF
OUR WEATHER THROUGH THE WEEKEND. THE RESULT WILL BE VFR CONDITIONS
AND GENERALLY LIGHT WINDS.
COULD SEE SOME SCT CUMULUS DEVELOP LATE THIS MORNING DUE TO
HEATING AND RESIDUAL LOW LEVEL MOISTURE. THE OOZ NAM SOUNDINGS IN
BUFKIT AND THE 08Z HRRR CLOUD BASE HEIGHT FORECASTS BOTH SHOW THE
LIKELIHOOD OF SCT LOW LEVEL CLOUDS AROUND 5000 FT FROM 16Z TIL
22Z TODAY.
MILLER
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT FRI AUG 17 2012
SHORT TERM...TODAY THROUGH MONDAY NIGHT
00Z MODELS ARE IN FAIR AGREEMENT WITH SYNOPTICS AND GENERALLY
FAVOR QUIET WEATHER DURING THIS NEXT WEEK WITH BELOW NORMAL TEMPS
THIS WEEKEND GRADUALLY WARMING BACK UP DURING MIDDLE AND LATER
PART OF NEXT WEEK. USED A BLEND OF THE WARM MET AND COOLER MAV
HIGHS THROUGH MONDAY WHILE LEANING ON COOLER MET GUIDANCE FOR LOWS
NEXT FEW NIGHTS.
STRONG COLD FRONT HAS PUSHED SE OF IL EARLY THIS MORNING AND
APPROACHING THE OHIO RIVER WITH CLEARING SKIES SPREADING SE TO A
CHAMPAIGN TO TAYLORVILLE LINE. SOME PATCHY FOG FROM
CHARLESTON/MATTOON SE TO LAWRENCEVILLE WITH MATTOON AIRPORT VSBY
LOWEST AT 3/4 MILE. PATCHY FOG SHOULD LIFT BY MID MORNING IN SE IL
WHILE CLOUDS DECREASE. SCATTERED CUMULUS CLOUDS TO DEVELOP BY LATE
MORNING INTO THE AFTERNOON ESPECIALLY OVER EASTERN IL WHERE PARTLY
TO MOSTLY SUNNY SKIES EXPECTED. HIGHS IN THE MID TO UPPER 70S WITH
LAWRENCEVILLE NEAR 80F. 1022 MB HIGH PRESSURE OVER SD/NE TO SETTLE
INTO IL SAT AND CONTINUE A FAIR AMOUNT OF SUNSHINE WITH HIGHS IN
THE UPPER 70S WITH SW AREAS NEAR 80F. STRONG UPPER LEVEL TROF
DIGGING SOUTHWARD FROM JAMES BAY INTO THE EASTERN STATES THIS
WEEKEND TO KEEP TEMPS A BIT BELOW NORMAL THROUGH MONDAY. SOME
MODELS SHOW WEAK SHORT WAVES IN NW FLOW MOVING NEAR IL SAT NIGHT
AND SUNDAY BUT LIMITED MOISTURE TO WORK WITH AND WILL KEEP A DRY
FORECAST WITH POPS ONLY 10%.
LONG TERM...TUESDAY THROUGH FRIDAY
STRONG UPPER LEVEL TROF TO GRADUALLY PULL AWAY FROM IL DURING
MIDDLE OF NEXT WEEK AS UPPER LEVEL RIDGE IN THE WEST SHIFTS EASTWARD
AND NOSES CLOSER TO IL LATER NEXT WORK WEEK. THIS TO GRADUALLY
WARM TEMPS BACK UP INTO THE MID TO UPPER 80S WITH SW AREAS AROUND 90F
LATER NEXT WEEK. GENERALLY DRY CONDITIONS EXPECTED TO CONTINUE
WITH TROPICAL MOISTURE STAYING SE OF IL AND WEATHER DISTURBANCES
PASSING NORTH AND WEST OF IL THROUGH NEXT FRIDAY. GFS SEEMS TOO
QUICK WITH BRINGING A COLD FRONT SE INTO IL LATER NEXT WEEK AND
LEANED TOWARD THE SLOWER ECMWF MODEL.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
633 AM CDT FRI AUG 17 2012
.DISCUSSION...
ISSUED 330 AM CDT FRI AUG 17 2012
SHORT TERM...TODAY THROUGH MONDAY NIGHT
00Z MODELS ARE IN FAIR AGREEMENT WITH SYNOPTICS AND GENERALLY
FAVOR QUIET WEATHER DURING THIS NEXT WEEK WITH BELOW NORMAL TEMPS
THIS WEEKEND GRADUALLY WARMING BACK UP DURING MIDDLE AND LATER
PART OF NEXT WEEK. USED A BLEND OF THE WARM MET AND COOLER MAV
HIGHS THROUGH MONDAY WHILE LEANING ON COOLER MET GUIDANCE FOR LOWS
NEXT FEW NIGHTS.
STRONG COLD FRONT HAS PUSHED SE OF IL EARLY THIS MORNING AND
APPROACHING THE OHIO RIVER WITH CLEARING SKIES SPREADING SE TO A
CHAMPAIGN TO TAYLORVILLE LINE. SOME PATCHY FOG FROM
CHARLESTON/MATTOON SE TO LAWRENCEVILLE WITH MATTOON AIRPORT VSBY
LOWEST AT 3/4 MILE. PATCHY FOG SHOULD LIFT BY MID MORNING IN SE IL
WHILE CLOUDS DECREASE. SCATTERED CUMULUS CLOUDS TO DEVELOP BY LATE
MORNING INTO THE AFTERNOON ESPECIALLY OVER EASTERN IL WHERE PARTLY
TO MOSTLY SUNNY SKIES EXPECTED. HIGHS IN THE MID TO UPPER 70S WITH
LAWRENCEVILLE NEAR 80F. 1022 MB HIGH PRESSURE OVER SD/NE TO SETTLE
INTO IL SAT AND CONTINUE A FAIR AMOUNT OF SUNSHINE WITH HIGHS IN
THE UPPER 70S WITH SW AREAS NEAR 80F. STRONG UPPER LEVEL TROF
DIGGING SOUTHWARD FROM JAMES BAY INTO THE EASTERN STATES THIS
WEEKEND TO KEEP TEMPS A BIT BELOW NORMAL THROUGH MONDAY. SOME
MODELS SHOW WEAK SHORT WAVES IN NW FLOW MOVING NEAR IL SAT NIGHT
AND SUNDAY BUT LIMITED MOISTURE TO WORK WITH AND WILL KEEP A DRY
FORECAST WITH POPS ONLY 10%.
LONG TERM...TUESDAY THROUGH FRIDAY
STRONG UPPER LEVEL TROF TO GRADUALLY PULL AWAY FROM IL DURING
MIDDLE OF NEXT WEEK AS UPPER LEVEL RIDGE IN THE WEST SHIFTS EASTWARD
AND NOSES CLOSER TO IL LATER NEXT WORK WEEK. THIS TO GRADUALLY
WARM TEMPS BACK UP INTO THE MID TO UPPER 80S WITH SW AREAS AROUND 90F
LATER NEXT WEEK. GENERALLY DRY CONDITIONS EXPECTED TO CONTINUE
WITH TROPICAL MOISTURE STAYING SE OF IL AND WEATHER DISTURBANCES
PASSING NORTH AND WEST OF IL THROUGH NEXT FRIDAY. GFS SEEMS TOO
QUICK WITH BRINGING A COLD FRONT SE INTO IL LATER NEXT WEEK AND
LEANED TOWARD THE SLOWER ECMWF MODEL.
KH
&&
.AVIATION...
ISSUED 633 AM CDT FRI AUG 17 2012
LATEST IR SATELLITE LOOP SHOWS THE WESTERN EDGE OF CLOUD BAND
SOUTH OF I-70 AT DAYBREAK. HIGH PRESSURE IN THE CENTRAL PLAINS
WILL DRIFT TOWARD THE MID MISSISSIPPI VALLEY AND BE IN CONTROL OF
OUR WEATHER THROUGH THE WEEKEND. THE RESULT WILL BE VFR CONDITIONS
AND GENERALLY LIGHT WINDS.
COULD SEE SOME SCT CUMULUS DEVELOP LATE THIS MORNING DUE TO
HEATING AND RESIDUAL LOW LEVEL MOISTURE. THE OOZ NAM SOUNDINGS IN
BUFKIT AND THE 08Z HRRR CLOUD BASE HEIGHT FORECASTS BOTH SHOW THE
LIKELIHOOD OF SCT LOW LEVEL CLOUDS AROUND 5000 FT FROM 16Z TIL
22Z TODAY.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1113 PM MDT THU AUG 16 2012
.UPDATE...
ISSUED AT 840 PM MDT THU AUG 16 2012
MADE MINOR ADJUSTMENTS TO POP/WX FORECAST FOR TONIGHT...KEEPING
CHANCE POPS IN FAR EASTERN CWA. 00Z HAS TRENDED FURTHER
SOUTH AND EAST WITH AXIS OF FRONOTGENETIC FORCING AND POSITIVE
THETA-E ADVECTION. I DIDNT WANT TO IGNORE THE LATEST RUC QPF WHICH
WOULD SUPPORT ACTIVITY FURTHER WEST...HOWEVER CONSIDERING THE BEST
LARGE SCALE SUPPORT DOESNT LOOK BE THERE I KEPT CHANCES LIMITED TO
20 PERCENT ACROSS MOST OF THE CWA. OVERALL TIMING FROM PREVIOUS
FORECAST STILL LOOKS GOOD WITH ANY SHOWERS/ISOLATED THUNDERSTORMS
DEVELOPING AROUND 09Z IN THE SOUTHEAST...SPREADING NORTH AND EAST
THROUGH FRIDAY MORNING BEFORE MOVING OUT OF OUR CWA AROUND 15Z.
UPDATE ISSUED AT 356 PM MDT THU AUG 16 2012
JUST COMPLETED MINOR UPDATE TO CAPTURE LATEST TREND REGARDING
POPS/SKY OVER WESTERN PARTS OF CWA. ACTIVITY OVER FRONT RANGE
CURRENTLY PROGRESSING EASTWARD TOWARDS WESTERN EXTENT OF CWA.
BASED ON LATEST RUC INSTABILITY REMAINS VERY WEAK OVER OUR CWA
AND THERE IS LITTLE IN THE WAY OF LARGE SCALE ASCENT. JUST BASED
ON CURRENT RADAR TRENDS AND RUC QPF I COULDNT RULE OUT AN ISOLATED
SHOWER OR THUNDERSTORM SNEAKING INTO WESTERN YUMA AND KIT CARSON
COUNTIES LATE THIS AFTERNOON OR EARLY THIS EVENING BEFORE DIURNAL
HEATING COMES TO AN END AND LOW LEVEL LAPSE RATES DECREASE. NO
OTHER SIGNIFICANT CHANGE MADE.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 210 PM MDT THU AUG 16 2012
18Z WATER VAPOR IMAGERY INDICATED AN UPPER LEVEL SHORT WAVE TROUGH
OVER THE NORTH CENTRAL CONUS...WITH THE TROUGH AXIS EXTENDING
SOUTHWEST INTO WESTERN KANSAS. AT THE SURFACE HIGH PRESSURE WAS
OVER THE NEBRASKA PANHANDLE...BUILDING SOUTHEAST. THE COLD FRONT WAS
BACKED UP AGAINST THE ROCKIES AND EXTENDED SOUTHEAST INTO THE TEXAS
PANHANDLE.
TONIGHT WINDS WILL BE LIGHT AS THE HIGH PRESSURE BUILDS INTO THE
AREA. DURING THE OVERNIGHT HOURS THE SURFACE HIGH MOVES EAST OF THE
AREA. MEANWHILE WARM AIR ADVECTION IN THE 750-650 MB LAYER AND
MOISTURE INCREASE OVER THE EASTERN PART OF THE AREA BEHIND THE
SURFACE HIGH. A DRY LAYER WILL REMAIN IN PLACE BELOW 750MB SO WILL
KEEP THE PRECIPITATION CHANCES IN THE SLIGHT CATEGORY.
EARLY FRIDAY MORNING WARM AIR ADVECTION INCREASES AND AN UPPER LEVEL
SHORT WAVE TROUGH MOVES OVER THE EASTERN HALF OF THE AREA.
INCREASED PRECIP. CHANCES DURING THE FIRST HALF OF THE MORNING WHEN
THE LIFT AND MOISTURE WILL BE GREATEST. DURING THE LATE MORNING AND
AFTERNOON THE BETTER ISENTROPIC LIFT/MOISTURE MOVE EAST WITH THE
SHORT WAVE TROUGH...BRINGING PRECIPITATION CHANCES TO AN END FROM WEST
TO EAST. DURING THE LATE AFTERNOON SURFACE CONVERGENCE/LIFT FROM A
700MB SHORT WAVE TROUGH DEVELOP OVER LINCOLN COUNTY CO. POINT
SOUNDINGS SHOW THE AIR MASS EITHER BEING TOO DRY OR CAPPED. HOWEVER
AS THE SURFACE HIGH MOVES EAST IT WILL DRAG THE FRONT ACROSS THE
WEST HALF OF AREA WITH IT. WILL INCLUDE LOW SLIGHT CHANCES OVER THE
FAR WEST DURING THE LATE AFTERNOON DUE TO THE SHORT WAVE AND FRONT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 210 PM MDT THU AUG 16 2012
NORTHWEST FLOW WILL CONTINUE THROUGH SUNDAY WITH A RIDGE OVER THE
ROCKIES AND AN UPPER LOW NORTH OF THE GREAT LAKES. SURFACE HIGH
PRESSURE WILL RESIDE OVER THE CENTRAL PLAINS THROUGH THIS TIME.
A SHORTWAVE COMES THROUGH THE FLOW FRIDAY NIGHT/EARLY SATURDAY. THE
BEST FORCING COMES ACROSS THE FA FRIDAY NIGHT WITH DYNAMICS EXITING
ALL BUT THE EASTERN FA SATURDAY MORNING. SUBSIDENCE MOVES INTO THE
FA SATURDAY AFTERNOON/NIGHT. SUBSIDENCE CONTINUES SUNDAY. 850-700
LAYER MEAN RH IS LIMITED WITH THE BEST MOISTURE JUST TO THE EAST OF
THE FA. DUE TO THE LIMITED MOISTURE WILL GO WITH SLIGHT CHANCE POPS
FRIDAY NIGHT/EARLY SATURDAY WITH NIL POPS SATURDAY AFTERNOON/NIGHT
THROUGH SUNDAY.
MIN TEMPERATURES WILL BE IN THE MID 50S FRIDAY NIGHT AND THE LOWER
TO MID 50S SATURDAY NIGHT. MAX TEMPERATURES WILL RISE TO THE LOWER
80S SATURDAY/SUNDAY.
FOR SUNDAY NIGHT THROUGH THURSDAY...A RIDGE WILL BE OVER THE ROCKIES
THROUGH THURSDAY. OTHER THAN SURFACE HIGH PRESSURE SUNDAY, A TROUGH
WILL EXIST OVER EASTERN COLORADO THROUGH THURSDAY.
SHORTWAVES IN THE FLOW WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS
MONDAY THROUGH TUESDAY NIGHT. DYNAMICS MOVE OFF TO THE NORTHEAST
WEDNESDAY WITH SUBSIDENCE FOLLOWING WEDNESDAY NIGHT/THURSDAY.
850 TEMPERATURES INDICATE STEADILY WARMER TEMPERATURES WITH MAX
TEMPERATURES IN THE MID 80S MONDAY WARMING TO THE LOWER 90S
WEDNESDAY COOLING SLIGHTLY TO THE UPPER 80S THURSDAY. MIN
TEMPERATURES WILL RANGE FROM THE LOWER 60S TO THE MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1112 PM MDT THU AUG 16 2012
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD AT BOTH KGLD AND
KMCK TERMINALS. LIGHT EASTERLY WINDS ARE EXPECTED OVERNIGHT. WINDS
WILL SHIFT TO THE SOUTHEAST AND INCREASE AFTER SUNRISE AS HIGH
PRESSURE SHIFTS EAST...WITH GUSTS AT KGLD AROUND 22KT. WINDS WILL
REMAINING AROUND 9KT AT KMCK THROUGH THE REMAINING TAF PERIOD.
CONFIDENCE IN PRECIP TONIGHT AT EITHER TERMINAL HAS GREATLY
DIMINISHED WITH SHORT RANGE GUIDANCE TRENDING MUCH DRIER...WITH
FOCUS STILL SOUTHEAST OF EITHER TERMINAL. THUNDERSTORMS MAY
DEVELOP IN THE WEST FRIDAY AFTERNOON AND MOVE EAST TOWARDS KGLD
AND KMCK FRIDAY EVENING...HOWEVER COVERAGE IS STILL A BIG QUESTION
SO I LEFT MENTION OUT OF TAFS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DR
SHORT TERM...FS
LONG TERM...JTL
AVIATION...DR
AREA FORECAST DISCUSSION
NWS JACKSON KY
146 PM EDT FRI AUG 17 2012
.UPDATE...
ISSUED AT 1235 PM EDT FRI AUG 17 2012
COLD FRONT SLOWLY PRESSING ACROSS THE STATE. AT 16Z FRONT EXTENDS
FROM JUST WEST OF FGX TO JUST EAST OF BWG. SCATTERED SHOWERS
DEVELOPING IN A LINE FROM JOHNSON COUNTY TO JACKSON COUNTY. EXPECT
LINE TO CONTINUE TO DEVELOP SW...AS THE LINE ITSELF PRESSES
SOUTHEAST. SHOWER THREAT HAS ENDED IN THE FAR NW PART OF FORECAST
AREA AND HAVE REMOVED RAIN CHANCES THERE. ALSO LOWERED RAIN
PROBABILITY TO NUMEROUS SHOWER TO SCATTERED THUNDERSTORM CHANCES
ELSEWHERE. HAVE UPDATED NDFD AND ZFP.
UPDATE ISSUED AT 953 AM EDT FRI AUG 17 2012
HAVE UPDATED NDFD AND ZFP BASED ON LATEST OBSERVATIONAL TRENDS.
EXTENSIVE CLOUDINESS WILL LIMIT DESTABILIZATION AND OVERALL
THUNDERSTORM CHANCES TODAY...BUT STILL EXPECT NUMEROUS TO WIDESPREAD
SHOWERS. BEST CHANCE FOR STRONGER THUNDERSTORMS WILL BE OVER THE
SOUTHEAST PART OF THE FORECAST AREA. 10Z HRRR IS SHOWING CONVECTION
DEVELOPING FROM MONTICELLO TO PAINTSVILLE THIS AFTERNOON AND THEN
MOVING SOUTHEAST.
UPDATE ISSUED AT 659 AM EDT FRI AUG 17 2012
UPDATED FOR CURRENT CONDITIONS/OBSERVED TRENDS. WITH LACK OF RETURNS
ON RADAR AND SLOWER PRECIP DEVELOPMENT IN 06Z RUNS...THIS INCLUDES
LATER DEVELOPMENT OF PRECIP THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 352 AM EDT FRI AUG 17 2012
A COLD FRONT WILL APPROACH FROM THE NW TODAY...AND TRANSITION ACROSS
THE REGION TONIGHT. EXTENSIVE CLOUD COVER WILL LIMIT
DESTABILIZATION. HOWEVER...THE RIGHT ENTRANCE REGION OF AN UPPER JET
COINCIDING WITH THE FRONT WILL AID IN SUPPORT FOR PRECIP. WILL CALL
FOR 70-80 PERCENT POPS...BUT ONLY A CHANCE FOR THUNDER.
AS DRIER AIR ARRIVES FROM NW TO SE THIS AFTERNOON AND TONIGHT...
PRECIP WILL TAPER OFF AND CLOUDS WILL DECREASE. THIS WILL LEAVE A DRY
DAY ON SATURDAY...WITH SURFACE HIGH PRESSURE TO OUR NW BEING OUR
DOMINANT FEATURE.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 352 AM EDT FRI AUG 17 2012
MODELS REMAIN IN FAIRLY GOOD AGREEMENT THROUGH THE BEGINNING OF NEXT
WEEK DEPICTING ANOTHER LOW MOVING INTO HUDSON BAY BEFORE UNDERGOING
AN AMPLIFICATION OF THE TROF OVER THE ERN CONUS...WITH NUMEROUS
SHORT WAVES RIPPLING AROUND THE BACKSIDE OF THE LOW TRANSITING THE
OHIO VALLEY FROM LATE THIS WEEKEND INTO EARLY NEXT WEEK. AT THE
SFC...GUIDANCE POINTS TOWARDS HIGH PRESSURE OVER THE PLAINS EARLY IN
THE PERIOD SLIDING EAST INTO THE REGION AND LINGERING OVER THE AREA
THROUGH ABOUT THE MIDDLE OF NEXT WEEK BEFORE SHIFTING FURTHER EAST
AND ULTIMATELY OPENING UP A RETURN FLOW OF WARMER...MOIST GOMEX AIR
LATE IN THE PERIOD.
THE 17.00Z ECMWF BRINGS ONE OF THESE WAVES THROUGH THE AREA ON
SUNDAY NIGHT INTO MONDAY WHILE THE CONSENSUS SUGGESTS QUITE A BIT OF
DEEP MOISTURE IN PLACE OVER THE AREA...AND HAVE INCLUDED A SLIGHT
CHANCE FOR THE SE AND HIGHER TERRAIN ALONG THE KY/VA LINE THROUGH
THIS TIME FRAME. THE NERN CONUS TROF BEGINS TO LIFT OFF TO THE NE BY
MID WEEK...SOMEWHAT FASTER IN THE LATEST GFS SOLUTION...WHILE THE
EURO DEVELOPS A CLOSED LOW OVER THE CONFLUENCE OF THE MS/OH RIVERS.
HAVE SPLIT THE DIFFERENCE HERE AND INTRODUCED ANOTHER ROUND OF
SLIGHT CHANCE POPS TO ROUND OUT THE LONG TERM.
TEMPS THROUGH THE PERIOD STILL LOOK TO START OUT BELOW NORMAL BEFORE
MODERATING AROUND THE MIDDLE OF NEXT WEEK TO NEAR AND ABOVE NORMAL
BY THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 146 PM EDT FRI AUG 17 2012
A COLD FRONT IS MOVING ACROSS THE AREA THIS AFTERNOON...BRINGING A
LINE OF SHOWERS AND A FEW THUNDERSTORMS TO THE SOUTHEASTERN PART OF
THE FORECAST AREA. THE SHOWERS ARE WELL AHEAD OF THE FRONT WHICH
EXTENDS FROM NEAR FGX TO GLW AT 17Z. JUST AHEAD OF AND BEHIND THE
FRONT THERE IS A LARGE AREA OF LOW CLOUDS WITH MVFR TO IFR CEILINGS.
EXPECT MVFR CEILINGS TO PREVAIL AT LOZ AND SME THIS AFTERNOON WITH
CEILINGS DECREASING TO IFR AT JKL. MOST OF THE SHOWERS WILL BE
SOUTHEAST OF THE TAF SITES BY 1830Z. THERE WILL BE SOME PARTIAL
CLEARING TONIGHT...WITH TEMPORARY VFR CONDITIONS. THE PARTIAL
CLEARING WILL SET THE STAGE FOR FOG FORMATION ESPECIALLY IN THE
SOUTHEAST PART OF THE FORECAST AREA WHERE RAIN WILL HAVE OCCURRED.
EXPECT IFR CONDITIONS IN FOG TO DEVELOP LATE TONIGHT...WITH
CONDITIONS IMPROVING TO VFR BY 14Z ON SATURDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...HAL
LONG TERM....MB
AVIATION...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1237 PM EDT FRI AUG 17 2012
.UPDATE...
ISSUED AT 1235 PM EDT FRI AUG 17 2012
COLD FRONT SLOWLY PRESSING ACROSS THE STATE. AT 16Z FRONT EXTENDS
FROM JUST WEST OF FGX TO JUST EAST OF BWG. SCATTERED SHOWERS
DEVELOPING IN A LINE FROM JOHNSON COUNTY TO JACKSON COUNTY. EXPECT
LINE TO CONTINUE TO DEVELOP SW...AS THE LINE ITSELF PRESSES
SOUTHEAST. SHOWER THREAT HAS ENDED IN THE FAR NW PART OF FORECAST
AREA AND HAVE REMOVED RAIN CHANCES THERE. ALSO LOWERED RAIN
PROBABILTY TO NUMEROUS SHOWER TO SCATTERED THUNDERSTORM CHANCES
ELSEWHERE. HAVE UPDATED NDFD AND ZFP.
UPDATE ISSUED AT 953 AM EDT FRI AUG 17 2012
HAVE UPDATED NDFD AND ZFP BASED ON LATEST OBSERVATIONAL TRENDS.
EXTENSIVE CLOUDINESS WILL LIMIT DESTABILIZATION AND OVERALL
THUNDERSTORM CHANCES TODAY...BUT STILL EXPECT NUMEROUS TO WIDESPREAD
SHOWERS. BEST CHANCE FOR STRONGER THUNDERSTORMS WILL BE OVER THE
SOUTHEAST PART OF THE FORECAST AREA. 10Z HRRR IS SHOWING CONVECTION
DEVELOPING FROM MONTICELLO TO PAINTSVILLE THIS AFTERNOON AND THEN
MOVING SOUTHEAST.
UPDATE ISSUED AT 659 AM EDT FRI AUG 17 2012
UPDATED FOR CURRENT CONDITIONS/OBSERVED TRENDS. WITH LACK OF RETURNS
ON RADAR AND SLOWER PRECIP DEVELOPMENT IN 06Z RUNS...THIS INCLUDES
LATER DEVELOPMENT OF PRECIP THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 352 AM EDT FRI AUG 17 2012
A COLD FRONT WILL APPROACH FROM THE NW TODAY...AND TRANSITION ACROSS
THE REGION TONIGHT. EXTENSIVE CLOUD COVER WILL LIMIT
DESTABILIZATION. HOWEVER...THE RIGHT ENTRANCE REGION OF AN UPPER JET
COINCIDING WITH THE FRONT WILL AID IN SUPPORT FOR PRECIP. WILL CALL
FOR 70-80 PERCENT POPS...BUT ONLY A CHANCE FOR THUNDER.
AS DRIER AIR ARRIVES FROM NW TO SE THIS AFTERNOON AND TONIGHT...
PRECIP WILL TAPER OFF AND CLOUDS WILL DECREASE. THIS WILL LEAVE A DRY
DAY ON SATURDAY...WITH SURFACE HIGH PRESSURE TO OUR NW BEING OUR
DOMINANT FEATURE.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 352 AM EDT FRI AUG 17 2012
MODELS REMAIN IN FAIRLY GOOD AGREEMENT THROUGH THE BEGINNING OF NEXT
WEEK DEPICTING ANOTHER LOW MOVING INTO HUDSON BAY BEFORE UNDERGOING
AN AMPLIFICATION OF THE TROF OVER THE ERN CONUS...WITH NUMEROUS
SHORT WAVES RIPPLING AROUND THE BACKSIDE OF THE LOW TRANSITING THE
OHIO VALLEY FROM LATE THIS WEEKEND INTO EARLY NEXT WEEK. AT THE
SFC...GUIDANCE POINTS TOWARDS HIGH PRESSURE OVER THE PLAINS EARLY IN
THE PERIOD SLIDING EAST INTO THE REGION AND LINGERING OVER THE AREA
THROUGH ABOUT THE MIDDLE OF NEXT WEEK BEFORE SHIFTING FURTHER EAST
AND ULTIMATELY OPENING UP A RETURN FLOW OF WARMER...MOIST GOMEX AIR
LATE IN THE PERIOD.
THE 17.00Z ECMWF BRINGS ONE OF THESE WAVES THROUGH THE AREA ON
SUNDAY NIGHT INTO MONDAY WHILE THE CONSENSUS SUGGESTS QUITE A BIT OF
DEEP MOISTURE IN PLACE OVER THE AREA...AND HAVE INCLUDED A SLIGHT
CHANCE FOR THE SE AND HIGHER TERRAIN ALONG THE KY/VA LINE THROUGH
THIS TIME FRAME. THE NERN CONUS TROF BEGINS TO LIFT OFF TO THE NE BY
MID WEEK...SOMEWHAT FASTER IN THE LATEST GFS SOLUTION...WHILE THE
EURO DEVELOPS A CLOSED LOW OVER THE CONFLUENCE OF THE MS/OH RIVERS.
HAVE SPLIT THE DIFFERENCE HERE AND INTRODUCED ANOTHER ROUND OF
SLIGHT CHANCE POPS TO ROUND OUT THE LONG TERM.
TEMPS THROUGH THE PERIOD STILL LOOK TO START OUT BELOW NORMAL BEFORE
MODERATING AROUND THE MIDDLE OF NEXT WEEK TO NEAR AND ABOVE NORMAL
BY THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 659 AM EDT FRI AUG 17 2012
A FEW LIGHT SHOWERS WERE IN THE AREA EARLY THIS MORNING. ADDITIONAL
SHOWERS ARE EXPECTED TO DEVELOP DURING THE DAY...WITH MOST LOCATIONS
ENDING UP WET. THERE MAY ALSO BE THUNDERSTORMS...BUT CONFIDENCE IN
WHEN AND WHERE IS TOO LOW TO ALLOW ADDRESSING IT IN TAFS. LOCALIZED
MVFR AND IFR IS POSSIBLE IN PRECIP DURING THE DAY...BUT PREVAILING
WEATHER SHOULD BE VFR. PRECIP SHOULD END FROM NW TO SE DURING THE
AFTERNOON AND EVENING.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...HAL
LONG TERM....MB
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
953 AM EDT FRI AUG 17 2012
.UPDATE...
ISSUED AT 953 AM EDT FRI AUG 17 2012
HAVE UPDATED NDFD AND ZFP BASED ON LATEST OBSERVATIONAL TRENDS.
EXTENSIVE CLOUDINESS WILL LIMIT DESTABILIZATION AND OVERALL
THUNDERSTORM CHANCES TODAY...BUT STILL EXPECT NUMEROUS TO WIDESPREAD
SHOWERS. BEST CHANCE FOR STRONGER THUNDERSTORMS WILL BE OVER THE
SOUTHEAST PART OF THE FORECAST AREA. 10Z HRRR IS SHOWING CONVECTION
DEVELOPING FROM MONTICELLO TO PAINTSVILLE THIS AFTERNOON AND THEN
MOVING SOUTHEAST.
UPDATE ISSUED AT 659 AM EDT FRI AUG 17 2012
UPDATED FOR CURRENT CONDITIONS/OBSERVED TRENDS. WITH LACK OF RETURNS
ON RADAR AND SLOWER PRECIP DEVELOPMENT IN 06Z RUNS...THIS INCLUDES
LATER DEVELOPMENT OF PRECIP THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 352 AM EDT FRI AUG 17 2012
A COLD FRONT WILL APPROACH FROM THE NW TODAY...AND TRANSITION ACROSS
THE REGION TONIGHT. EXTENSIVE CLOUD COVER WILL LIMIT
DESTABILIZATION. HOWEVER...THE RIGHT ENTRANCE REGION OF AN UPPER JET
COINCIDING WITH THE FRONT WILL AID IN SUPPORT FOR PRECIP. WILL CALL
FOR 70-80 PERCENT POPS...BUT ONLY A CHANCE FOR THUNDER.
AS DRIER AIR ARRIVES FROM NW TO SE THIS AFTERNOON AND TONIGHT...
PRECIP WILL TAPER OFF AND CLOUDS WILL DECREASE. THIS WILL LEAVE A DRY
DAY ON SATURDAY...WITH SURFACE HIGH PRESSURE TO OUR NW BEING OUR
DOMINANT FEATURE.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 352 AM EDT FRI AUG 17 2012
MODELS REMAIN IN FAIRLY GOOD AGREEMENT THROUGH THE BEGINNING OF NEXT
WEEK DEPICTING ANOTHER LOW MOVING INTO HUDSON BAY BEFORE UNDERGOING
AN AMPLIFICATION OF THE TROF OVER THE ERN CONUS...WITH NUMEROUS
SHORT WAVES RIPPLING AROUND THE BACKSIDE OF THE LOW TRANSITING THE
OHIO VALLEY FROM LATE THIS WEEKEND INTO EARLY NEXT WEEK. AT THE
SFC...GUIDANCE POINTS TOWARDS HIGH PRESSURE OVER THE PLAINS EARLY IN
THE PERIOD SLIDING EAST INTO THE REGION AND LINGERING OVER THE AREA
THROUGH ABOUT THE MIDDLE OF NEXT WEEK BEFORE SHIFTING FURTHER EAST
AND ULTIMATELY OPENING UP A RETURN FLOW OF WARMER...MOIST GOMEX AIR
LATE IN THE PERIOD.
THE 17.00Z ECMWF BRINGS ONE OF THESE WAVES THROUGH THE AREA ON
SUNDAY NIGHT INTO MONDAY WHILE THE CONSENSUS SUGGESTS QUITE A BIT OF
DEEP MOISTURE IN PLACE OVER THE AREA...AND HAVE INCLUDED A SLIGHT
CHANCE FOR THE SE AND HIGHER TERRAIN ALONG THE KY/VA LINE THROUGH
THIS TIME FRAME. THE NERN CONUS TROF BEGINS TO LIFT OFF TO THE NE BY
MID WEEK...SOMEWHAT FASTER IN THE LATEST GFS SOLUTION...WHILE THE
EURO DEVELOPS A CLOSED LOW OVER THE CONFLUENCE OF THE MS/OH RIVERS.
HAVE SPLIT THE DIFFERENCE HERE AND INTRODUCED ANOTHER ROUND OF
SLIGHT CHANCE POPS TO ROUND OUT THE LONG TERM.
TEMPS THROUGH THE PERIOD STILL LOOK TO START OUT BELOW NORMAL BEFORE
MODERATING AROUND THE MIDDLE OF NEXT WEEK TO NEAR AND ABOVE NORMAL
BY THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 659 AM EDT FRI AUG 17 2012
A FEW LIGHT SHOWERS WERE IN THE AREA EARLY THIS MORNING. ADDITIONAL
SHOWERS ARE EXPECTED TO DEVELOP DURING THE DAY...WITH MOST LOCATIONS
ENDING UP WET. THERE MAY ALSO BE THUNDERSTORMS...BUT CONFIDENCE IN
WHEN AND WHERE IS TOO LOW TO ALLOW ADDRESSING IT IN TAFS. LOCALIZED
MVFR AND IFR IS POSSIBLE IN PRECIP DURING THE DAY...BUT PREVAILING
WEATHER SHOULD BE VFR. PRECIP SHOULD END FROM NW TO SE DURING THE
AFTERNOON AND EVENING.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...HAL
LONG TERM....MB
AVIATION...HAL
AREA FORECAST DISCUSSION
NWS GRAY ME
637 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL MOVE ACROSS NORTHERN NEW ENGLAND
TONIGHT BRINGING SCATTERED SHOWERS AND THUNDERSTORMS WITH IT. THE
FRONT WILL STALL OVER THE GULF OF MAINE AS LOW PRESSURE MOVES
ALONG IT SATURDAY INTO SUNDAY. AT THE PRESENT TIME IT LOOKS LIKE
MOST OF THE CLOUDS AND RAIN WITH THIS SYSTEM WILL STAY JUST EAST
OF THE REGION.
&&
.NEAR TERM /THROUGH SATURDAY/...
UPDATE...
CONVECTION CONTS TO MARCH EASTWARD...MUCH IN LINE WITH THE SAME
OVERALL PATTERN SHOWN IN THE LATEST HRRR MODEL. HAVE INCLUDED THE
POSSIBILITY OF GUSTY WINDS AND HAIL TO THE GRIDS AS WELL AS SOME
OF THE STMS ARE NOW SHOWING CORES WELL ABV THE FRZG LVL. HAVE ALSO
INCREASED POPS IN A LINE MOVG EASTWARD INTO CTNRL ME OVER THE NEXT
FEW HRS.
MADE A FEW ADJUSTMENTS TO CLOUD COVER AND DEW POINTS AS WELL.
OTRW...FCST WILL REMAIN RELATIVELY UNCHANGED.
PREV DISC...
MOSTLY SUNNY SKIES ACROSS THE REGION THIS AFTERNOON WITH DEW
POINTS MAINLY IN THE 50S TO LOWER 60S. A WEAK FRONTAL BOUNDARY IS
APPROACHING THE CWA FROM THE WEST. INSTABILITY AHEAD OF THE FRONT
IS AT BEST WEAK. APPEARS AS THOUGH THE NAM HAS A LITTLE BETTER
HANDLE ON THIS FEATURE THAN THE GFS DOES. ONLY ISOLATED SHOWERS
POPPING UP OVER THE ADIRONDACKS TO THE WEST OF US WHERE
INSTABILITY IS BETTER. BECAUSE OF THIS...WILL BACK OFF OF POPS A
BIT THIS AFTERNOON AND EVENING...ESPECIALLY OVER THE MOUNTAINS.
BOUNDARY LOOKS AS THOUGH IT WILL WASH OUT QUITE A BIT AS IT MOVES
ACROSS THE AREA.
&&
.SHORT TERM /SATURDAY NIGHT/...
THE FRONTAL BOUNDARY WILL STALL JUST OFFSHORE EARLY SATURDAY. THIS
LOOKS LIKE IT WILL BE THE TRICKIEST PART OF THE FORECAST. THE NAM
TAKES THE BOUNDARY INTO THE GULF OF MAINE SATURDAY MORNING. IT
DEVELOPS A WAVE THAT MOVES ALONG THE BOUNDARY AND PRODUCES SOME
PRECIPITATION JUST OFFSHORE. THE GFS ON THE OTHER HAND...KEEPS THE
BOUNDARY ALONG THE COAST AND GENERATES PRECIPITATION TOMORROW
MORNING ALONG THE COAST OF MAINE. AGAIN...FEEL AS THOUGH THE NAM
IS HANDLING THIS FEATURE BETTER DUE TO INITIALIZATION OF
CONVECTION OVER NEW YORK STATE TODAY. ONCE THE BOUNDARY IS CLEAR
OF THE COAST...HIGH PRESSURE WILL BUILD IN FOR TOMORROW NIGHT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
FRONTAL SYSTEM WITH DEPARTING LOW WILL KEEP CLOUDS AND SHOWER
THREAT OVER THE COASTAL WATERS ON SUNDAY. EXPECT LAND AREAS TO
REMAIN DRY. CLOUDS ALONG THE IMMEDIATE COAST COULD BE PROBLEMATIC
DEPENDING ON HOW QUICKLY THE FRONT PUSHES EAST. HAVE GONE WITH A
EURO-GFS SOLUTION AS THE NAM IS SLOWER IN MOVING THE FRONT EAST.
WEAK RIDGING WILL KEEP THINGS DRY SUNDAY NIGHT INTO MONDAY. A WEAK
TROUGH WILL CROSS THE AREA LATE MONDAY INTO MONDAY NIGHT. THIS
MAY BRING A FEW SHOWERS WITH IT.
TUE-FRI THE AREA WILL BE UNDER A CYCLONIC FLOW ALOFT. WHILE NO
LARGE SCALE PRECIPITATION EVENT IS FORECAST...A FEW SHOWERS ARE
POSSIBLE ESPECIALLY DIURNALLY OVER THE MOUNTAINS. IN ADDITION ANY SHORT
WAVES MOVING THROUGH THIS CYCLONIC FLOW COULD TRIGGER SHOWERS.
TIMING OF THESE SUBTLE FEATURES IN THE LONG RANGE PORTION OF THE
FORECAST IS DIFFICULT. TEMPERATURES SHOULD BE NEAR NORMAL.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL INTO THE EVENING HOURS.
AN APPROACHING BOUNDARY MAY GENERATE SOME SCATTERED SHOWERS AND
THUNDERSTORMS THIS EVENING. EXPECT RADIATION FOG TO SET UP AGAIN
TONIGHT AND DROP VSBY AND CIGS TO IFR/LIFR BY MORNING. FOG SHOULD
NOT BE AS THICK AS LAST NIGHT AND IS EXPECTED TO BURN OFF QUICKER.
LONG TERM...MAINLY MVFR CONDITIONS EXPECTED.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED.
LONG TERM...WINDS AND SEAS WILL REMAIN BELOW SCA LEVELS.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAY ME
528 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL MOVE ACROSS NORTHERN NEW ENGLAND
TONIGHT BRINGING SCATTERED SHOWERS AND THUNDERSTORMS WITH IT. THE
FRONT WILL STALL OVER THE GULF OF MAINE AS LOW PRESSURE MOVES
ALONG IT SATURDAY INTO SUNDAY. AT THE PRESENT TIME IT LOOKS LIKE
MOST OF THE CLOUDS AND RAIN WITH THIS SYSTEM WILL STAY JUST EAST
OF THE REGION.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
UPDATE...
HAVE UPDATED GRIDS BASED ON ONGOING CONVECTION PER LATEST KGYX
IMAGES. SHOWERS AND ISOLD TSTMS WILL CONT TO MOVE EASTWARD INTO
MAINE OVER THE NEXT HOUR. ANOTHER ROUND OF STMS WILL CROSS INTO
THE CT RVR VLY BY AROUND 6 PM OR SO AS WELL. THIS IS BEING PICKED
UP WELL BY THE LATEST HRRR MODEL.
MADE A FEW ADJUSTMENTS TO CLOUD COVER AND DEW POINTS AS WELL.
OTRW...FCST WILL REMAIN RELATIVELY UNCHANGED.
PREV DISC...
MOSTLY SUNNY SKIES ACROSS THE REGION THIS AFTERNOON WITH DEW
POINTS MAINLY IN THE 50S TO LOWER 60S. A WEAK FRONTAL BOUNDARY IS
APPROACHING THE CWA FROM THE WEST. INSTABILITY AHEAD OF THE FRONT
IS AT BEST WEAK. APPEARS AS THOUGH THE NAM HAS A LITTLE BETTER
HANDLE ON THIS FEATURE THAN THE GFS DOES. ONLY ISOLATED SHOWERS
POPPING UP OVER THE ADIRONDACKS TO THE WEST OF US WHERE
INSTABILITY IS BETTER. BECAUSE OF THIS...WILL BACK OFF OF POPS A
BIT THIS AFTERNOON AND EVENING...ESPECIALLY OVER THE MOUNTAINS.
BOUNDARY LOOKS AS THOUGH IT WILL WASH OUT QUITE A BIT AS IT MOVES
ACROSS THE AREA.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
THE FRONTAL BOUNDARY WILL STALL JUST OFFSHORE EARLY SATURDAY. THIS
LOOKS LIKE IT WILL BE THE TRICKIEST PART OF THE FORECAST. THE NAM
TAKES THE BOUNDARY INTO THE GULF OF MAINE SATURDAY MORNING. IT
DEVELOPS A WAVE THAT MOVES ALONG THE BOUNDARY AND PRODUCES SOME
PRECIPITATION JUST OFFSHORE. THE GFS ON THE OTHER HAND...KEEPS THE
BOUNDARY ALONG THE COAST AND GENERATES PRECIPITATION TOMORROW
MORNING ALONG THE COAST OF MAINE. AGAIN...FEEL AS THOUGH THE NAM
IS HANDLING THIS FEATURE BETTER DUE TO INITIALIZATION OF
CONVECTION OVER NEW YORK STATE TODAY. ONCE THE BOUNDARY IS CLEAR
OF THE COAST...HIGH PRESSURE WILL BUILD IN FOR TOMORROW NIGHT.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
FRONTAL SYSTEM WITH DEPARTING LOW WILL KEEP CLOUDS AND SHOWER
THREAT OVER THE COASTAL WATERS ON SUNDAY. EXPECT LAND AREAS TO
REMAIN DRY. CLOUDS ALONG THE IMMEDIATE COAST COULD BE PROBLEMATIC
DEPENDING ON HOW QUICKLY THE FRONT PUSHES EAST. HAVE GONE WITH A
EURO-GFS SOLUTION AS THE NAM IS SLOWER IN MOVING THE FRONT EAST.
WEAK RIDGING WILL KEEP THINGS DRY SUNDAY NIGHT INTO MONDAY. A WEAK
TROUGH WILL CROSS THE AREA LATE MONDAY INTO MONDAY NIGHT. THIS
MAY BRING A FEW SHOWERS WITH IT.
TUE-FRI THE AREA WILL BE UNDER A CYCLONIC FLOW ALOFT. WHILE NO
LARGE SCALE PRECIPITATION EVENT IS FORECAST...A FEW SHOWERS ARE
POSSIBLE ESPECIALLY DIURNALLY OVER THE MOUNTAINS. IN ADDITION ANY SHORT
WAVES MOVING THROUGH THIS CYCLONIC FLOW COULD TRIGGER SHOWERS.
TIMING OF THESE SUBTLE FEATURES IN THE LONG RANGE PORTION OF THE
FORECAST IS DIFFICULT. TEMPERATURES SHOULD BE NEAR NORMAL.
&&
.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS WILL PREVAIL INTO THE EVENING HOURS.
AN APPROACHING BOUNDARY MAY GENERATE SOME SCATTERED SHOWERS AND
THUNDERSTORMS THIS EVENING. EXPECT RADIATION FOG TO SET UP AGAIN
TONIGHT AND DROP VSBY AND CIGS TO IFR/LIFR BY MORNING. FOG SHOULD
NOT BE AS THICK AS LAST NIGHT AND IS EXPECTED TO BURN OFF QUICKER.
LONG TERM...MAINLY MVFR CONDITIONS EXPECTED.
&&
.MARINE...
SHORT TERM...NO FLAGS EXPECTED.
LONG TERM...WINDS AND SEAS WILL REMAIN BELOW SCA LEVELS.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
826 PM EDT SAT AUG 18 2012
.SYNOPSIS...
A COLD FRONT WILL STALL OUT OVER NORTH CAROLINA TONIGHT. THE
BOUNDARY WILL RETURN NORTH AS A WARM FRONT LATE SUNDAY. A WAVE OF
LOW PRESSURE MAY DEVELOP ALONG THE BOUNDARY SUNDAY NIGHT INTO
MONDAY. HIGH PRESSURE WILL SLOWLY BUILD DURING THE MIDDLE PORTION
OF THE WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
COLD FRONT HAS STALLED OUT ACROSS NORTH CAROLINA THIS EVENING.
HIGH PRESSURE WILL BUILD IN FROM THE NW FOR THE REMAINDER OF THE NIGHT.
ISOLATED SHOWERS CONTINUE TO DEVELOP ACROSS THE SOUTHERN POTOMAC
HIGHLANDS THIS EVENING. PREVIOUS RUNS OF THE HRRR DID HAVE THIS
ACTIVITY...WITH IT DIMINISHING SHORTLY AFTER SUNSET. TWEAKED POPS
A BIT FOR THE SHOWERS. IN ADDITION...DID HAVE TO TWEAK THE HOURLY
TEMPS AND DEWS TO REFLECT CURRENT TRENDS.
MOISTURE RETURN IN TANDEM WITH SOME WARM ADVECTION AND EVENTUAL
ISENTROPIC LIFT WILL NOT ONLY LEAD TO INCREASING CLOUDS ON
SUNDAY...BUT ALSO A CHANCE OF SHOWERS ESPECIALLY ALONG AND WEST OF
THE BLUE RIDGE.
MAXIMA SUNDAY ARE FORECAST TO RISE TO AROUND TODAY/S VALUES...UPPER
70S WEST OF THE BLUE RIDGE...LOWER TO POSSIBLY MID 80S EAST OF THE
BLUE RIDGE.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
AN UPPER-LEVEL TROUGH WILL BE CENTERED TO OUR WEST ACROSS THE GREAT
LAKES AND TENNESSEE VALLEY WHILE A STATIONARY BOUNDARY REMAINS
OVERHEAD. A SERIES OF UPPER-LEVEL DISTURBANCES WILL ROTATE AROUND
THE TROUGH DURING THIS TIME...BRINGING PLENTY OF CLOUDS ALONG WITH
UNSETTLED CONDITIONS. ONE OF THESE DISTURBANCES WILL LIKELY CAUSE A
WAVE OF SURFACE LOW PRESSURE TO DEVELOP ALONG THE FRONT SUNDAY NIGHT
INTO MONDAY. TRACK AND LOCATION OF THIS LOW IS UNCERTAIN AT THIS
TIME...BUT IT DOES APPEAR THERE WILL BE AN ENHANCED THREAT FOR
SHOWERS DURING THIS TIME. LOW PRESSURE WILL LIKELY MOVE OFF TO THE
NORTHEAST MONDAY NIGHT.
MAX TEMPS MONDAY WILL BE A FEW DEGREES BELOW CLIMO DUE TO THE CLOUD
COVER...RANGING FROM THE UPPER 60S AND LOWER 70S IN THE ALLEGHENY
AND POTOMAC HIGHLANDS TO THE UPPER 70S AND LOWER 80S ACROSS MOST
OTHER LOCATIONS.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
THE UPPER-LEVEL TROUGH AND STATIONARY BOUNDARY WILL WILL REMAIN
OVERHEAD TUESDAY. A COUPLE SHOWERS AND THUNDERSTORMS CANNOT BE RULED
OUT...BUT THERE WILL BE SOME SUNSHINE AND IT WILL NOT BE A WASHOUT
SINCE THE SURFACE LOW WILL BE WELL OFF TO THE NORTH AND EAST.
THE TROUGH AXIS WILL GRADUALLY LIFT OUT OF THE REGION GIVING WAY TO
A ZONAL FLOW DURING THE MIDDLE AND LATTER PORTIONS OF THE WEEK.
SURFACE HIGH PRESSURE WILL ALSO BUILD TOWARD THE REGION...ALLOWING
FOR DRY AND SEASONABLE CONDITIONS DURING THIS TIME.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
THROUGH TONIGHT...MAINLY VFR CONDITIONS EXPECTED...DRIER AIR WILL
COVER THE REGION TONIGHT UNDER MAINLY CLEAR SKIES. FOR CHO...MVFR
VSBYS EXPECTED AFTER 08Z IN FOG BUT SOME MID-HIGH LVL CLOUDS SHOULD
HELP KEEP FOG FROM DROPPING BELOW VFR.
FOR SUN...MID-LVL 100-150 KFT CLOUDS EXPECTED TO OVERSPREAD THE
REGION FROM SW TO NE STARTING AFTER 12Z...BUT DRY CONDITIONS AND VFR
VSBYS EXPECTED.
LOW PRESSURE WILL CAUSE SHOWERS SUNDAY NIGHT THROUGH MONDAY NIGHT. A
FLOW OFF THE ATLANTIC OCEAN WILL ALSO CAUSE SUBVFR CIGS/VSBYS DURING
THIS TIME.
VFR CONDITIONS WILL RETURN FOR THE MIDDLE PORTION OF THE WEEK.
ISOLATED SHOWERS/T-STORMS ARE POSSIBLE TUESDAY.
&&
.MARINE...
NORTHERLY FLOW CONTINUES DOWN THE BAY...BUT RELATIVELY WEAK GRADIENT
HAS KEPT WINDS IN CHECK /I.E. BELOW SCA CRITERIA/ AT 10 TO 15 KT.
EXPECT WINDS TO REMAIN AT THIS LEVEL THROUGH SUNDAY...AS WIND
DIRECTION SHIFTS MORE TOWARD THE EAST THROUGH THE DAY.
LOW PRESSURE WILL BRING UNSETTLED CONDITIONS TO THE WATERS SUNDAY
NIGHT THROUGH MONDAY NIGHT. WIND SPEEDS SHOULD REMAIN BELOW SCA
CRITERIA DURING THIS TIME.
A STATIONARY BOUNDARY MAY TRIGGER A COUPLE SHOWERS/T-STORMS
TUESDAY...BUT DRIER WEATHER SHOULD RETURN DURING THE MIDDLE AND
LATTER PORTIONS OF THE WEEK AS HIGH PRESSURE BUILDS TOWARD THE
WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
LISTEMAA/ZUBRICK
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1131 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE UPPER OHIO VALLEY TODAY ACCOMPANIED BY
SOME SHOWERS AND THUNDERSTORMS. COOLER AND DRIER WEATHER WILL
FOLLOW FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH 8 PM THIS EVENING/...
AN UPDATE HAS BEEN ISSUED TO ACCOUNT FOR THE LATEST RADAR AND TEMP
TRENDS AS A COLD FRONT CROSSES THE AREA.
THE LATEST SURFACE ANALYSIS INDICATES A COLD FRONT EXTENDING ALONG
A NEW MARTINSVILLE-WAYNESBURG-LATROBE LINE. THE FRONT IS MOST
INDICATIVE BY WINDS SHIFTING TO WESTERLY AND BY IR/WV SAT
IMAGERY. ASIDE FROM THE WIND SHIFT, THE TEMP AND TD GRADIENTS ARE
WEAK ALONG THE FRONT WITH A MORE GRADUAL DECREASE IN TDS UPSTREAM.
SHOWERS ARE MOSTLY ALONG AND BEHIND THE FRONT.
THIS AFTERNOON...THE FRONT WILL CONTINUE TO MOVE EASTWARD TO THE
RIDGES, SLOWING AS IT CROSSES THEM. WITH THE FRONT, SCATTERED TO
NUMEROUS SHOWERS CAN BE EXPECTED FOR A FEW HOURS INTO THE EARLY
AFTERNOON BEFORE COMING TO AN END. THE STORM PREDICTION CENTER HAS A
PORTION OF THE SOUTHEAST RIDGES HIGHLIGHTED IN ITS MOST RECENT DAY 1
OUTLOOK. DESPITE THE RAP INDICATING AROUND 1000 J/KG SBCAPE AND
40KTS 0-6KM SHEAR, BELIEVE CLOUD COVERAGE AND WEAK FORCING WILL BE
INHIBITORS TO THE DEVELOPMENT OF SEVERE THIS AFTERNOON. A FEW
THUNDERSTORMS CANNOT BE RULED OUT. QPF WILL GENERALLY BE LESS
THAN A QUARTER OF AN INCH ACROSS THE AREA WITH THE HIGHEST AMOUNTS
ALONG THE SOUTHEAST RIDGES.
TEMP FORECAST IS CHALLENGING TODAY AS WEAK COLD AIR ADVECTION
BATTLES SUNSHINE BEHIND THE FRONT. FORECAST CONSISTS OF A
HRRR/LAMP BLEND WITH TEMPS ADJUSTED DOWN ALONG RAIN-COOLED PRECIP
AREA ALONG THE FRONT. AFTER THE FRONT PUSHES EAST, TEMPS WILL
WARM INTO THE MID 70S ACROSS MUCH OF THE AREA LATE THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
THE FRONT IS PROJECTED SOUTH OF THE AREA BY THIS EVENING AND POPS
HAVE BEEN TAPERED OFF. COOL AND DRY SURFACE HIGH PRES...UNDER A
BROAD TROUGH ALOFT...WILL SUPPORT TEMPS OF 5 TO 10 DEGREES BELOW
NORMAL...AND A DRY WEEKEND FOR MOST COUNTIES. THE EXCEPTION MAY BE
OVER THE RIDGES WHERE A CROSSING DISTURBANCE AND UPSLOPE FLOW ON
SUNDAY MAY SUPPORT SOME ISOLATED SHOWERS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
KEPT MENTION OF ISOLATED SHOWERS ALONG THE RIDGES SUNDAY NIGHT INTO
MONDAY AS AN UPPER TROUGH REMAINS OVER THE GREAT LAKES REGION WHILE
A WEAK SURFACE LOW CROSSES THE SOUTHEASTERN STATES. THE REMAINDER OF
THE EXTENDED PERIOD SHOULD BE DRY AS A SURFACE RIDGE BUILDS EASTWARD
ACROSS THE UPPER OHIO VALLEY.
TEMPERATURES ARE FORECAST TO BE 5 TO 10 DEGREES BELOW NORMAL THROUGH
TUESDAY...THEN RETURN TO NEAR NORMAL BY MIDWEEK.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
COLD FRONT INTO EASTERN OHIO AT 12Z WITH ONLY SCATTERED SHOWERS
ALONG AND BEHIND FRONT. STILL EXPECT MORE DEVELOPMENT LATER TODAY
ALONG FRONT WITH HIGHEST POPS TOWARD THE I-80 CORRIDOR AND THE
SOUTHEAST RIDGES. FOR THE TERMINALS THIS BRINGS A PERIOD OF MVFR
TODAY WITH THE FRONT. WINDS WILL SHIFT TO THE NORTHWEST THIS
AFTERNOON NEAR 10KTS. TONIGHT FRONT WILL EXIT SOUTHEAST WITH DRY
HIGH PRESSURE BRINING GENERAL VFR.
.OUTLOOK/ SATURDAY THROUGH TUESDAY/... GENERALLY VFR WEATHER IS
ANTICIPATED UNDER A WEAK SURFACE RIDGE...WITH NO WIDESPREAD
PRECIPITATION OR RESTRICTIONS ANTICIPATED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1150 PM EDT SAT AUG 18 2012
.SYNOPSIS...
ISSUED AT 342 PM EDT SAT AUG 18 2012
A DEPARTING HIGH PRESSURE SYSTEM SHOULD CLEAR THE SKIES EARLY
TONIGHT. HOWEVER A COLD FRONT MOVING SOUTH THROUGH THE AREA SUNDAY
WILL BRING SOME SHOWERS AND ISOLATED THUNDERSTORMS TO NORTHERN
SECTIONS AFTER MIDNIGHT. AS THE FRONT MOVES THROUGH THE AREA
SUNDAY EXPECT SHOWERS AND ISOLATED THUNDERSTORMS. TEMPERATURES
WILL REMAIN BELOW NORMAL INTO TUESDAY BEFORE A SLOW WARMING TREND
SETS IN.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 342 PM EDT SAT AUG 18 2012
THE PRIMARY ISSUE WITH THIS FORECAST IS CONVECTION AND THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS INTO MONDAY.
A WEAK CONVERGENCE BOUNDARY FROM NEAR MKG TO MBS THIS AFTERNOON IS
INTERACTING WITH THE LAKE BREEZE AND A WEAK MID LEVEL SHORTWAVE TO
CAUSE A CLUSTER OF SHOWERS AND ISOLATED THUNDERSTORMS THAT
CONTINUES TO MOVE EAST FROM NEWAYGO COUNTY INTO MONTCALM COUNTY.
THIS ACTIVITY IS MOVING VERY SLOWLY... ONLY 10 MPH AND SHOULD
DISSIPATE BY SUNSET OVER GRATIOT AND ISABELLA COUNTIES. AREAS NEAR
AND SOUTH OF INTERSTATE 96 SHOULD STAY DRY. DUE TO THE DRY SUB
CLOUD LAYER EXPECT SOME GUSTY WINDS WITH THE STORMS. WE HAVE SEEN
GUSTS TO AROUND 20 MPH SO FAR. A MESO-NET IN THE CITY OF NEWAYGO HAD
A QUARTER INCH OF RAIN FROM THE STORMS THIS AFTERNOON SO FAR.
AS THE COLD FRONT DROPS SOUTH OVERNIGHT INTO SUNDAY THE SURFACE
PRESSURE GRADIENT IS WEAK. WITH THE SURFACE WATERS OF LAKE
MICHIGAN NEAR 22C AND AIR TEMPS EXPECTED TO FALL INTO THE 50S
INLAND AN LAND BREEZE WILL ONCE AGAIN SET UP. WITH THAT AND THE
FRONT MOVING SOUTH THE NAM12 SHOWS A MESO LOW FORMING THIS EVENING
NEAR TVC THE MOVING SOUTH TO LITTLE SABLE POINT BY MID MORNING
SUNDAY. THIS SHOULD FOCUS INSTABILITY NEAR THE LAKE SHORE AS IT
MOVES SOUTH OVERNIGHT. THERE IS ENOUGH INSTABILITY FOR
THUNDERSTORMS BASED ON BOTH RAP AND NAM SOUNDINGS. SO I INCREASED
POPS NORTH TONIGHT.
THIS BOUNDARY WILL SLOWLY MOVE SOUTH SUNDAY INTO SUNDAY EVENING.
THERE IS INSTABILITY BUT MARGINAL MOISTURE. EVEN SO GIVEN THE
CONVECTION THAT OCCURRED TODAY I BELIEVE SHOWERS ARE LIKELY NORTH
OF INTERSTATE 96 SUNDAY. WITH THE DRY SUB CLOUD LAYER EXPECT
GUSTY WINDS WITH THE SHOWERS AND THUNDERSTORMS. WITH THE COLD AIR
ALOFT EXPECT SMALL HAIL WITH THE STRONGER STORM TOO.
ONCE THE DRIER AIR BEHIND THE FRONT MOVES IN SUNDAY NIGHT SKIES
SHOULD CLEAR FROM NORTH TO SOUTH. WINDS WILL ONCE AGAIN BE LIGHT
SO ANOTHER LAKE BREEZE CONVERGENCE BAND OVER LAKE MICHIGAN IS
LIKELY TO FORM (SOUNDING REALLY SUPPORT THIS).
THERE IS STILL ENOUGH INSTABILITY WITH THE COLD AIR ALOFT FOR
AFTERNOON SHOWERS AND ISOLATED THUNDERSTORMS MONDAY. HOWEVER THE
MOISTURE IS ANEMIC. SO I WENT WITH ISOLATED SHOWERS /THUNDERSTORMS
FOR NOW.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 342 PM EDT SAT AUG 18 2012
WILL LEAVE TUESDAY DRY...BUT CAN NOT COMPLETELY RULE OUT A SHOWER AS
A SHORT WAVE CLEARS THE CWA. BEYOND THAT THE MID WEEK PERIOD LOOKS
QUIET AND PLEASANT AS LARGE HIGH PRESSURE SLIDES IN. THE HIGH
BECOMES BLOCKED BY AN UPPER LOW OVER THE CANADIAN MARITIME...SO
COMFORTABLE WEATHER SHOULD PREVAIL FOR A FEW DAYS. THE RIDGE
FINALLY MOVES EAST LATE IN THE WEEK WHICH ALLOWS A NORTHERN STREAM
SHORT WAVE TO APPROACH. WILL START POPS FRIDAY NIGHT IN THE WEST...
THEN SPREAD OVER ENTIRE CWA SATURDAY.
AS FOR TEMPS...WE SHOULD SEE A SLIGHT MODERATING TREND...BUT STAYING
NEAR NORMAL MUCH OF THE TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 1150 PM EDT SAT AUG 18 2012
VFR CONDITIONS EXPECTED THROUGH SUNDAY MORNING. THERE WILL BE AN
INCREASE IN CLOUDS AND THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS
SUNDAY AFTERNOON. WE WILL CARRY VCTS FOR THE AFTERNOON AS
INSTABILITY AND COVERAGE OF STORMS INCREASES. CLOUDS AND STORMS WILL
DECREASE AFTER SUNSET. WINDS SHOULD BE AOB 10 KNOTS THROUGH THE
FORECAST PERIOD EXCEPT FOR BRIEF WIND GUSTS IN ANY STORMS THAT
DO FORM SUNDAY AFTERNOON.
&&
.MARINE...
ISSUED AT 342 PM EDT SAT AUG 18 2012
WINDS WILL FOR THE MOST PART BE LESS THAN 15 KNOTS THROUGH MONDAY.
THUS I SEE NO NEED FOR A SMALL CRAFT ADVISORY AT THIS TIME. EVEN
SO THERE IS UNSEASONABLY COOL AIR IN PLACE AND LAKE MICHIGAN IS
STILL WARM RELATIVE TO THE AIR OVER IT... SO WITH THE CONVECTION
EXPECTED LATER TONIGHT AND SUNDAY EXPECT ISOLATED WATER SPOUTS
WITH THE STRONG SHOWERS AND THUNDERSTORMS. I ADDED THEM TO THE
GRIDS INTO SUNDAY AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 342 PM EDT SAT AUG 18 2012
WHILE THERE WILL BE SHOWERS AROUND INTO MONDAY I DO NOT EXPECT ANY
WIDESPREAD HEAVY RAINFALL. THUS NO BIG HYDRO ISSUES ARE FORESEEN AT
THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...JK
AVIATION...OSTUNO
HYDROLOGY...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
756 PM EDT SAT AUG 18 2012
.SYNOPSIS...
ISSUED AT 342 PM EDT SAT AUG 18 2012
A DEPARTING HIGH PRESSURE SYSTEM SHOULD CLEAR THE SKIES EARLY
TONIGHT. HOWEVER A COLD FRONT MOVING SOUTH THROUGH THE AREA SUNDAY
WILL BRING SOME SHOWERS AND ISOLATED THUNDERSTORMS TO NORTHERN
SECTIONS AFTER MIDNIGHT. AS THE FRONT MOVES THROUGH THE AREA
SUNDAY EXPECT SHOWERS AND ISOLATED THUNDERSTORMS. TEMPERATURES
WILL REMAIN BELOW NORMAL INTO TUESDAY BEFORE A SLOW WARMING TREND
SETS IN THAT WILL LAST NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 342 PM EDT SAT AUG 18 2012
THE PRIMARY ISSUE WITH THIS FORECAST IS CONVECTION AND THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS INTO MONDAY.
A WEAK CONVERGENCE BOUNDARY FROM NEAR MKG TO MBS THIS AFTERNOON IS
INTERACTING WITH THE LAKE BREEZE AND A WEAK MID LEVEL SHORTWAVE TO
CAUSE A CLUSTER OF SHOWERS AND ISOLATED THUNDERSTORMS THAT
CONTINUES TO MOVE EAST FROM NEWAYGO COUNTY INTO MONTCALM COUNTY.
THIS ACTIVITY IS MOVING VERY SLOWLY... ONLY 10 MPH AND SHOULD
DISSIPATE BY SUNSET OVER GRATIOT AND ISABELLA COUNTIES. AREAS NEAR
AND SOUTH OF INTERSTATE 96 SHOULD STAY DRY. DUE TO THE DRY SUB
CLOUD LAYER EXPECT SOME GUSTY WINDS WITH THE STORMS. WE HAVE SEEN
GUSTS TO AROUND 20 MPH SO FAR. A MESO-NET IN THE CITY OF NEWAYGO HAD
A QUARTER INCH OF RAIN FROM THE STORMS THIS AFTERNOON SO FAR.
AS THE COLD FRONT DROPS SOUTH OVERNIGHT INTO SUNDAY THE SURFACE
PRESSURE GRADIENT IS WEAK. WITH THE SURFACE WATERS OF LAKE
MICHIGAN NEAR 22C AND AIR TEMPS EXPECTED TO FALL INTO THE 50S
INLAND AN LAND BREEZE WILL ONCE AGAIN SET UP. WITH THAT AND THE
FRONT MOVING SOUTH THE NAM12 SHOWS A MESO LOW FORMING THIS EVENING
NEAR TVC THE MOVING SOUTH TO LITTLE SABLE POINT BY MID MORNING
SUNDAY. THIS SHOULD FOCUS INSTABILITY NEAR THE LAKE SHORE AS IT
MOVES SOUTH OVERNIGHT. THERE IS ENOUGH INSTABILITY FOR
THUNDERSTORMS BASED ON BOTH RAP AND NAM SOUNDINGS. SO I INCREASED
POPS NORTH TONIGHT.
THIS BOUNDARY WILL SLOWLY MOVE SOUTH SUNDAY INTO SUNDAY EVENING.
THERE IS INSTABILITY BUT MARGINAL MOISTURE. EVEN SO GIVEN THE
CONVECTION THAT OCCURRED TODAY I BELIEVE SHOWERS ARE LIKELY NORTH
OF INTERSTATE 96 SUNDAY. WITH THE DRY SUB CLOUD LAYER EXPECT
GUSTY WINDS WITH THE SHOWERS AND THUNDERSTORMS. WITH THE COLD AIR
ALOFT EXPECT SMALL HAIL WITH THE STRONGER STORM TOO.
ONCE THE DRIER AIR BEHIND THE FRONT MOVES IN SUNDAY NIGHT SKIES
SHOULD CLEAR FROM NORTH TO SOUTH. WINDS WILL ONCE AGAIN BE LIGHT
SO ANOTHER LAKE BREEZE CONVERGENCE BAND OVER LAKE MICHIGAN IS
LIKELY TO FORM (SOUNDING REALLY SUPPORT THIS).
THERE IS STILL ENOUGH INSTABILITY WITH THE COLD AIR ALOFT FOR
AFTERNOON SHOWERS AND ISOLATED THUNDERSTORMS MONDAY. HOWEVER THE
MOISTURE IS ANEMIC. SO I WENT WITH ISOLATED SHOWERS /THUNDERSTORMS
FOR NOW.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 342 PM EDT SAT AUG 18 2012
WILL LEAVE TUESDAY DRY...BUT CAN NOT COMPLETELY RULE OUT A SHOWER AS
A SHORT WAVE CLEARS THE CWA. BEYOND THAT THE MID WEEK PERIOD LOOKS
QUIET AND PLEASANT AS LARGE HIGH PRESSURE SLIDES IN. THE HIGH
BECOMES BLOCKED BY AN UPPER LOW OVER THE CANADIAN MARITIME...SO
COMFORTABLE WEATHER SHOULD PREVAIL FOR A FEW DAYS. THE RIDGE
FINALLY MOVES EAST LATE IN THE WEEK WHICH ALLOWS A NORTHERN STREAM
SHORT WAVE TO APPROACH. WILL START POPS FRIDAY NIGHT IN THE WEST...
THEN SPREAD OVER ENTIRE CWA SATURDAY.
AS FOR TEMPS...WE SHOULD SEE A SLIGHT MODERATING TREND...BUT STAYING
NEAR NORMAL MUCH OF THE TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 756 PM EDT SAT AUG 18 2012
VFR CONDITIONS EXPECTED TONIGHT. INCREASE IN CLOUDS AND THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON. WE WILL
CARRY VCTS FOR THE AFTERNOON AS INSTABILITY AND COVERAGE OF STORMS
INCREASES. WINDS SHOULD BE AOB 10 KNOTS THROUGH THE FORECAST
PERIOD EXCEPT FOR BRIEF THUNDERSTORM WIND GUSTS IN ANY STORMS THAT
DO FORM SUNDAY AFTERNOON.
&&
.MARINE...
ISSUED AT 342 PM EDT SAT AUG 18 2012
WINDS WILL FOR THE MOST PART BE LESS THAN 15 KNOTS THROUGH MONDAY.
THUS I SEE NO NEED FOR A SMALL CRAFT ADVISORY AT THIS TIME. EVEN
SO THERE IS UNSEASONABLY COOL AIR IN PLACE AND LAKE MICHIGAN IS
STILL WARM RELATIVE TO THE AIR OVER IT... SO WITH THE CONVECTION
EXPECTED LATER TONIGHT AND SUNDAY EXPECT ISOLATED WATER SPOUTS
WITH THE STRONG SHOWERS AND THUNDERSTORMS. I ADDED THEM TO THE
GRIDS INTO SUNDAY AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 342 PM EDT SAT AUG 18 2012
WHILE THERE WILL BE SHOWERS AROUND INTO MONDAY I DO NOT EXPECT ANY
WIDESPREAD HEAVY RAINFALL. THUS NO BIG HYDRO ISSUES ARE FORESEEN AT
THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...JK
AVIATION...OSTUNO
HYDROLOGY...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
729 PM EDT SAT AUG 18 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 359 PM EDT SAT AUG 18 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER
ERN NAMERICA CENTERED AROUND CUTOFF UPR LO NEAR JAMES BAY. THERE ARE
SEVERAL SHRTWVS ROTATING THRU THE TROF AND ARND THIS FEATURE. THE
FIRST IS SETTLING S THRU ONTARIO WHILE ANOTHER NEAR LK WINNIPEG IS
DIVING SSEWD TOWARD NW MN. AT 15Z...THESE SHRTWVS/ACCOMPANYING SFC
TROF OVER LK SUP WITH SHARP WSHFT WERE SUPPORTING A BKN LINE OF SHRA
EXTENDING FM ERN LK SUP ACRS THE KEWEENAW THRU NRN MN TOWARD LK
WINNIPEG. THE 12Z INL RAOB SHOWS ABUNDANT MID LVL MSTR ABV A DRIER
SUB H75 LYR...AND THIS LOWER LVL DRY AIR SEEMS TO BE THE BIGGEST
IMPEDIMENT TO MORE WDSPRD SHRA. THE DRY AIR IS DEEPER TO THE S AS
INDICATED BY THE 12Z GRB RAOB...AND THE MRNG WAS MOSUNNY OVER THE
SCNTRL. TO THE N...MUCH DRIER LLVL AIR IS PRESENT ON THE 12Z YPL
RAOB UNDER HI PRES RDG AXIS EXTENDING SEWD INTO NW ONTARIO FM HI
PRES CENTERED OVER NRN MANITOBA. MODIFIED
LATE THIS AFTN...WITH ARRIVAL OF SFC TROF/ENHANCED LLVL CNVGC
ASSOCIATED WITH SHARP SYNOPTIC WSHFT THAT WL BE ENHANCED BY
BREEZE OFF LK SUP DURING PEAK HEATING TIME...THE SHRA HAVE BECOME
MORE NMRS WITH SOME EMBEDDED TS ON A LINE THRU THE CNTRL ZNS.
MODIFIED 12Z INL RAOB FOR SFC T/TD OF 75/47 YIELDS SBCAPE UP TO 600
J/KG. ALTHOUGH SHRA COVERAGE IS STILL LIMITED OVER THE SCNTRL BY
LINGERING LLVL DRY AIR...EXPECT THESE SHRA TO SPREAD INTO THAT AREA
AS THE DRY AIR RETREATS. THE INTENSITY OF THE TS WL BE LIMITED BY
DRY LLVL AIR...ENVIRONMENTAL LAPSE RATES NOT FAR FM MOIST
ADIABATIC/DEEP SKINNY CAPE...LACK OF MID LVL DRY AIR THAT KEEPS
SFC-10K FT DELTA THETA-E NO HIER THAN 5-10C...AND RELATIVELY WEAK
DEEP LYR SHEAR NO GREATER THAN 15-25 KTS. ALTHOUGH SOME STORMS HAVE
PULSED AT TIMES...THE SMALL CORES HAVE NOT PERSISTED AND REMAINED
NEARLY VERTICAL...CONSISTENT WITH A WEAK SHEAR ENVIRONMENT. LO FRZG
LVL NOT FAR FM 9K FT AGL INDICATES THE STRONGER CELLS MIGHT DROP
SOME SMALL HAIL.
TONIGHT...MAIN FCST CONCERNS BECOME HOW QUICKLY DRIER AIR OVER
ONTARIO CAN MOVE INTO THE UPR LKS AND COUNTER LINGERING DYNAMIC
SUPPORT ASSOCIATED WITH DISTURBANCE NOW NEAR LK WINNIPEG THAT IS
FCST TO DROP SEWD INTO NW WI BY 12Z SUN AND SHARPEN UPR TROF AXIS
EXTENDING FM CLOSED LO NEAR JAMES BAY SWWD THRU UPR MI. LOSS OF
DAYTIME HEATING WL ALSO ENHANCE SHRA DISSIPATION. THE NAM IS MOST
AGGRESSIVE WITH UPR DRYING AND SHOWS ANY LINGERING -SHRA OVER THE
SCNTRL ENDING BY 03Z. THE BULK OF THE OTHER GUIDANCE MAINTAINS THE
-SHRA MAINLY OVER THE SCNTRL THRU MUCH OF THE NGT. HOWEVER...
CONSIDERING THE LLVL DRYNESS OF THE 12Z YPL RAOB AND RATHER
AGGRESSIVE DRYING TAKING PLACE OVER THE N PORTIONS OF LK SUP/
ADJOINING ONTARIO...THE NAM MIGHT BE ON THE RIGHT TRACK. SINCE ALL
THE MODELS ALSO SHOW LIMITED DEEP LYR QVECTOR CVNGC AS ANY DPVA
AHEAD OF SHRTWV IS OFFSET BY DRYING...TENDED TO CUT POPS A BIT
FASTER THAN GOING FCST WITH SMALL CHC POPS LINGERING ONLY OVER THE
FAR SCNTRL NEAR MNM LATER TNGT. ALTHOUGH LGT WINDS ASSOCIATED WITH
BLDG HI PRES MOVING TOWARD WRN UPR MI TOWARD 12Z/AGGRESSIVE MID LVL
DRYING MIGHT SUPPORT FOG FORMATION ESPECIALLY IN AREAS THAT GET RA
THIS AFTN/EVNG...WL KEEP FOG OUT OF FCST EXCEPT FOR OVER THE
INTERIOR WCNTRL...WHERE THE GFS HINTS THE LLVL DRYING WL BE LESS
PRONOUNCED AND SREF PROB VSBY UNDER 1 MILE IS HIER AND WHERE MIN
TEMPS ARE LIKELY TO BE LOWEST ARND 40.
SUN...CWA IS FCST TO REMAIN UNDER UPR TROF EXTENDING SWWD FM HUDSON
BAY. THE 12Z NAM/LOCAL WRF-ARW SHOW A SFC RDG AXIS EXTENDING FM WRN
LK SUP THRU THE CWA BRINGING A DRY DAY. THE 12Z GFS/CNDN MODELS ON
OTHER HAND SHOW A WEAKER SFC RDG...WITH A WEAKER GRADIENT ALLOWING
SOME LK BREEZE CNVGC/WEAK LO PRES TROF OVER THE SCNTRL...WHERE THESE
MODELS GENERATES SOME INSTABILITY -SHRA IN THE AFTN. CONSIDERING THE
WARM/DRY H7-5 LYR/LO FCST KINX ARND 18 BY THE GFS IN THIS AREA...
OPTED TO MAINTAIN GOING DRY FCST. WITH H85 TEMPS FCST TO BE ARND 8C
AND MIXING TO H75 ON GFS FCST SDNGS...EXPECT HI TEMPS TO REACH THE
MID 70S NEAR THE WI BORDER/SCNTRL AWAY FM LK MODERATION.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 359 PM EDT SAT AUG 18 2012
UPPER-LEVEL CONDITIONS WILL REMAIN SUPPORTIVE OF A SUBTLE SERIES OF
TROUGHS AND RIDGES THROUGH MONDAY. DRY CONDITIONS WILL THEN BUILD IN
FOR THE MIDDLE OF THE WEEK BEFORE A WARM...AND POTENTIALLY WET...END
TO THE WEEK.
SUNDAY NIGHT AND MONDAY...NAM/GFS/ECMWF/GEM HAVE COME INTO GOOD
AGREEMENT ON THE SYNOPTIC PATTERN ACROSS CENTRAL AND EASTERN NORTH
AMERICA THROUGH TUESDAY...SO OVERALL CONFIDENCE OF THE FORECAST IN
THIS TIME PERIOD IS FAIRLY GOOD.
A PERSISTENT MID-LEVEL LOW OVER JAMES BAY WILL BEGIN TO MOVE
NORTHEAST SUNDAY NIGHT AS A BROAD MID-LEVEL RIDGE OVER THE WESTERN
THIRD OF THE CONUS COMMENCES DEAMPLIFICATION WHILE DRIFTING EASTWARD
TOWARD THE UPPER GREAT LAKES REGION. A SERIES OF SHORTWAVE TROUGHS
WILL CONTINUE TO TRACK AROUND THE BACKSIDE OF THE LOW OVER JAMES
BAY. THE FIRST OF THOSE IS MOVING THROUGH THE AREA TODAY. THEN...A
SECOND TROUGH BEHIND TODAYS TROUGH WILL CROSS THE AREA ON
SUNDAY...AND BE EXITING TO THE SOUTHEAST OUT OF UPPER MI BY SUNDAY
EVENING. A SHORTWAVE RIDGE WILL THEN BRIEFLY MOVE IN SUNDAY EVENING
AHEAD OF YET ANOTHER WEAK SHORTWAVE TROUGH CROSSING THE CWA ON
MONDAY.
THE WEAK INCOMING RIDGE COMBINED WITH PLENTY OF DRY AIR THROUGHOUT
THE COLUMN SHOULD LIMIT THE CHANCE OF ANY PRECIP BY SUNDAY EVENING.
ATTENTION IS PLACED MOSTLY ON THE POTENTIAL OF TEMPERATURES NEARING
FROST CRITERIA/ 36F/ INTERIOR WEST SUNDAY NIGHT. DIFFICULTY OF
PINNING DOWN EXACT LOW TEMPS RESIDES WITH WINDS AND THE CLOUD COVER
PATTERN BETWEEN THE TROUGH ON MONDAY AND THE ONE ON TUESDAY.
FIRST...DRY AIR AND SUBSIDENCE WILL ERODE REMAINING CLOUDS FROM
SUNDAYS SHORTWAVE. SEVERAL MODELS ARE SHOWING AN ENHANCED LAYER OF
MOISTURE BETWEEN 800 AND 700MB MOVING INTO THE AREA LATE SUNDAY
NIGHT. THIS IS LIKELY RESIDUAL MOISTURE FROM DIURNAL CUMULUS ON
SUNDAY...AS IS NOTED WITH THE UPSTREAM SATELLITE IMAGES IN NORTHERN
MANITOBA...SO DO NOT THINK LOW CLOUDS WILL BE A FACTOR. AIR ABOVE
THE MID-LEVELS WILL BE QUITE DRY...WHICH IS ALSO NOTED ON IR/VIS
SATELLITE IMAGES FROM UPSTREAM. BEHIND A WEAK SFC RIDGE SUNDAY
EVENING...WINDS MAY END UP BEING THE LIMITING FACTOR AS THE PRESSURE
GRADIENT INCREASES WITH HIGH PRESSURE UNDER THE WESTERN RIDGE
BUILDING INTO THE REGION. THE LOW-LEVELS SHOULD BE ABLE TO DECOUPLE
ENOUGH...ESPECIALLY IN THE TYPICAL COLD SPOTS. ULTIMATELY...WILL
KEEP ONGOING FORECAST OF MID TO UPPER 30S WELL INLAND...AND LEAVE
PATCHY FROST OUT OF THE FORECAST FOR RIGHT NOW.
THE THIRD SHORTWAVE TROUGH IS PROGGED TO MOVE ACROSS THE CWA
THROUGHOUT THE DAY ON MONDAY. NOT MUCH IN THE WAY OF MOISTURE WITH
THIS SHORTWAVE EITHER. HOWEVER...AS THE INFLUENCE FROM THE TROUGH
APPROACHES THE SOUTH CENTRAL CWA...H8 WAA/MOISTURE TRANSPORT MAY
ASSIST WITH KICKING OFF SOME ISOLATED SHOWERS. LOW-LEVEL DRY AIR MAY
INHIBIT SHOWERS SOMEWHAT...SO WILL ONLY PUT A SLIGHT CHANCE IN THE
FORECAST FOR THE SOUTH-CENTRAL CWA. H8 TEMPS AROUND 7-8C SHOULD
YIELD HIGHS AROUND 70 FOR MOST LOCATIONS.
MONDAY NIGHT AND TUESDAY...THE DE-AMPLIFYING RIDGE FROM THE WESTERN
STATES WILL MOVE OVER UPPER MI MONDAY NIGHT...LEADING TO MOSTLY
CLEAR SKIES AND ANOTHER ROUND OF GOOD RADIATIONAL COOLING. THIS
TIME...DEW POINTS WILL BE MUCH HIGHER...SO MOST INLAND LOCATIONS
SHOULD STAY ABOVE 40. SUBSIDENCE FROM THE RIDGE WILL KEEP CONDITIONS
DRY THROUGH TUESDAY. H8 TEMPS FROM 10-12C WOULD RESULT IN MID 70S
FOR HIGHS ACROSS MOST OF THE CWA ON TUESDAY...WITH SLIGHTLY COOLER
TEMPS EAST IN REGIONS AFFECTED BY LAKE BREEZES FROM LAKES MICHIGAN
AND SUPERIOR.
TUESDAY NIGHT THROUGH SATURDAY...THE REMNANTS OF THE LOW CURRENTLY
OVER JAMES BAY WILL BE IN FAR NORTHERN QUEBEC BY TUESDAY NIGHT. A
SHORTWAVE TROUGH ROTATING AROUND THE BACK OF THE LOW IS PROGGED
TO MOVE THROUGH NORTHERN ONTARIO TUESDAY NIGHT INTO WEDNESDAY. THE
ECMWF HAS BEEN TRENDING FARTHER NORTH WITH THIS SYSTEM. MEANWHILE
THE GFS HAS BECOME THE MORE SOUTHERN SOLUTION. PREFER THE TREND OF
THE ECMWF AS THE WAVE WILL BE ATTEMPTING TO DIG INTO THE EASTERN
EDGE OF A NOW BUILDING WESTERN RIDGE. EXPECTATION IS THAT PRECIP
WILL STAY OUT OF THE AREA UNTIL LATE WEDNESDAY AS AN ASSOCIATED SFC
COLD FRONT STALLS OVER LAKE SUPERIOR...THOUGH THE FINAL LOCATION OF
THIS FEATURE IS STILL A LITTLE INCONSISTENT IN THE MODELS.
DRY AIR ABOVE THE LOWEST FEW KFT WILL ALLOW FOR DECENT MIXING ON
BOTH TUESDAY AND WEDNESDAY. LOWERED DAYTIME DEW POINTS ABOUT 5F FROM
PREVIOUS FORECAST FOR BOTH DAYS. THIS RESULTS IN MIN RH VALUES
AROUND 40 PERCENT BOTH DAYS. HOWEVER...FEELING IS THAT THE TREND
WILL BE TOWARD LOWER RH VALUES WITH PROCEEDING FORECASTS.
A DEEP TROUGH MOVING ONTO THE WEST COAST TUESDAY WILL THEN REACH THE
UPPER MS VALLEY BY LATE FRIDAY. THE INDUCED SFC LOW IS EXPECTED TO
BRING THE STALLED SFC BOUNDARY BACK NORTHWARD AS A WARM FRONT. HIGH
TEMPS DURING THIS TIME WILL LIKELY BE ABOVE NORMAL /AROUND 80/ DUE
TO SOUTHERLY FLOW SOUTH OF THE STALLED BOUNDARY...BUT AS NOTED
BEFORE...UNCERTAINTY STILL EXISTS IN THE FINAL LOCATION OF THE
BOUNDARY. WILL STICK WITH CONSENSUS OF MODEL THROUGHOUT THIS TIME
FRAME GIVEN DECENT AGREEMENT FOR THIS FAR OUT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 728 PM EDT SAT AUG 18 2012
AFTER LOW PRESSURE TROUGH/UPPER LEVEL DISTURBANCE PASSED THROUGH THE
TAF SITES...SHRA HAS SINCE COME TO AN END ACROSS KSAW AND KCMX.
CURRENT RADAR SHOWS ANOTHER BAND OF -SHRA THAT COULD IMPACT KIWD FOR
THE NEXT FEW HOURS...BUT RECENT DIMINISHING TRENDS HAVE LED TO NO
MENTION IN THE TAFS. HOWEVER...CONTINUED MOISTURE AT KIWD AND
SUBSIDENCE MOVING IN OVERNIGHT COULD SEE SOME BR
DEVELOPMENT...THOUGH EXACT VIS/CIG RESTRICTIONS ARE STILL UNCERTAIN
AT THIS TIME. CAN/T RULE OUT SOME PATCHY BR AT KCMX AND KSAW AS WELL
WITH LIGHT WINDS AND STABLE LAYER...HOWEVER LONGER DRYING PERIOD
THIS EVENING COULD INHIBIT LOW LEVEL MOISTURE SO LEFT OUT OF TAFS AS
CONFIDENCE IS FAIRLY LOW. OTHERWISE...HIGH PRESSURE AND VFR
CONDITIONS SHOULD PREVAIL THROUGH THE DAY TOMORROW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT SAT AUG 18 2012
A GENERALLY WEAK PRES GRADIENT DOMINATING THE UPPER GREAT LAKES WILL
RESULT IN WINDS MOSTLY UNDER 20KT THRU THU. THE PRES GRADIENT WILL
BECOME A BIT SHARPER TUE NIGHT AS A LO PRES TROF MOVES ACROSS
CENTRAL ONTARIO...RESULTING IN WSW WINDS UP TO 25 KTS OVER PORTIONS
OF THE W AND NORTH CENTRAL.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TK
AVIATION...JMW
MARINE...KC
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
704 PM CDT SAT AUG 18 2012
.AVIATION...
00Z TAFS FOR KOMA...KLNK AND KOFK.
CLOUDS IN THE 4000 TO 10000 FOOT LAYER WILL DECREASE THIS EVENING
AND SKIES WILL CLEAR AS WEAK HIGH PRESSURE BUILDS OVER THE AREA.
THIS WILL ALLOW SOME PATCHY FOG TO DEVELOP...WITH LIGHT WINDS.
FOR NOW...EXPECT JUST MVFR CONDITIONS WITH THE FOG.
MILLER
&&
.PREV DISCUSSION... /ISSUED 316 PM CDT SAT AUG 18 2012/
DISCUSSION...
SCATTERED SHOWERS CONTINUE TO SLIDE SOUTHEAST AS FORCING FOR
ASCENT FROM A MID LEVEL SHORTWAVE CONTINUES TO MOVE SOUTHEAST THRU
THE FORECAST AREA. THERE IS ANOTHER AREA OF SHOWERS IN A BAND TO
THE NORTHEAST OF THE CWA WHICH SEEMS TO LINE UP WELL WITH A NARROW
BAND OF MID LEVEL FRONTOGENESIS ON NOSE OF THETA-E AXIS. THIS
IS FORECAST TO CONTINUE SOUTHEAST THRU THE LATE AFTERNOON AND
EVENING HOURS SO WL CONTINUE TO INCLUDE A SMALL MENTION OF POPS IN
OUR EASTERN COUNTIES FOR THIS ACTIVITY AS WELL. IN
ADDITION...THERE IS A POTENTIAL FOR FOG DEVELOPMENT OVERNIGHT WITH
CLEARING SKIES. SFC WIND BECOMES LIGHT AND VARIABLE AS HIGH
PRESSURE MOVES OVER AREAS THAT SAW SOME PRECIPITATION TODAY.
LATEST HRRR ALSO SHOWING AREA OF REDUCED VISIBILITIES...ESPECIALLY
IN OUR NORTH SO WL GO AHEAD AND MENTION SOME PATCHY FOG OVERNIGHT.
EXPECTING LOWS TO FALL INTO THE UPPER 40S TO LOWER 50S WHICH
WILL BE CLOSE BUT SLIGHTLY ABOVE RECORDS.
SUNDAY CONTINUES TO LOOK MOSTLY DRY AS HIGH PRESSURE SLIDES EAST OF
THE AREA. MODELS CONTINUE TO INDICATE SOME LIGHT QPF IN OUR EASTERN
COUNTIES ASSOCIATED WITH EXITING UPPER LEVEL SHORTWAVE ENERGY. MAY
HAVE SOME ISOLATED SHOWERS OVER IOWA COUNTIES IN THE AFTERNOON
ONCE CU FIELD DEVELOPS. WILL THROW IN A SLIGHT CHANCE POP IN OUR
FAR NERN COUNTIES FOR SUNDAY AFTERNOON AND MENTION ISOLATED
THUNDER AS SOME INSTABILITY IS PRESENT.
AREA REMAINS IN NORTHWESTERLY FLOW FOR EARLY IN THE SCHOOL/WORK
WEEK. THE WEATHER SHOULD REMAIN FAIRLY QUIET WITH WARM SOUTHERLY
FLOW BRINGING A SLIGHT INCREASE IN LOW LEVEL MOISTURE TO THE
AREA.
IN THE EXTENDED...MID LEVEL FLOW WILL BECOME MORE ZONAL BY MID
WEEK AS WEAKENING UPPER LEVEL RIDGE FLATTENS OVER THE NATIONS MID
SECTION. A POTENT SHORTWAVE MOVING INTO THE NORTHERN PLAINS BY
LATE IN THE WEEK WILL DRIVE A COOL FRONT THRU THE CENTRAL PLAINS.
AHEAD OF THIS BOUNDARY...LOW LEVEL WARM AIR AND MOIST ADVECTION
COULD LEAD TO A SCATTERED CHANCE OF SHOWERS AND THUNDERSTORMS
THURSDAY. SEVERE THREAT WOULD LIKELY REMAIN FAR TO OUR
NORTH...CLOSER TO POTENT SHORTWAVE ENERGY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
408 PM CDT FRI AUG 17 2012
.SHORT TERM...THROUGH SATURDAY DAYTIME. PRIMARY ISSUE DURING THE
NEXT 24 HOURS IS TRYING TO PIN DOWN HIGH WIDESPREAD
SHOWER/THUNDERSTORM ACTIVITY WILL BE LATE TONIGHT INTO THE DAYTIME
SATURDAY...AND THE RESULTANT EFFECTS ON HIGH TEMPERATURES.
19Z OBJECTIVE SURFACE ANALYSIS REVEALS AN INCREDIBLY PLEASANT
AFTERNOON ACROSS THE CWA WITH VERY LIGHT BREEZES...THANKS TO A
1020MB RIDGE AXIS PARKED DIRECTLY OVER THE AREA AND EXTENDING
NORTHEAST INTO MN. VISIBLE SATELLITE CONFIRMS NEARLY CLOUD-FREE
SKIES ACROSS THE NORTHEAST 1/2 OF THE CWA...WHILE IN THE
SOUTHWEST...WHAT WAS A FAIRLY SOLID MID LEVEL CLOUD DECK A FEW
HOURS AGO HAS STEADILY ERODED/SCATTERED OUT QUITE A BIT. WATER
VAPOR SATELLITE IMAGERY ALONG WITH SHORT TERM MODEL DATA DEPICTS
THE CWA UNDER SEASONABLY STRONG NORTHWEST FLOW ALOFT...SANDWICHED
BETWEEN A LARGE SCALE TROUGH OVER THE NORTHEAST CONUS WHICH IS
ANCHORED BY A VIGOROUS VORT MAX OVER EASTERN QUEBEC...AND A BROAD
RIDGE CENTERED FROM THE INTERMOUNTAIN WEST TO SOUTH TX. THE QUICK
MOVING SHORTWAVE/SPEED MAX THAT WILL BRING PRECIP CHANCES LATE
TONIGHT INTO SATURDAY IS CURRENTLY EVIDENT DROPPING SOUTHEAST NEAR
THE MT/ND/CANADA BORDER. TEMPS THIS AFTERNOON ARE VERY MUCH ON
TRACK WITH PREVIOUS FORECAST HIGHS...AND MAY ACTUALLY EXCEED THEM
SLIGHTLY IN SOME AREAS AS A FEW POTS ARE MAKING A RUN AT REACHING
80. AS SUGGESTED IN THE EARLIER UPDATE DISCUSSION...LIMITED MIXING
INTO VERY DRY AIR ALOFT HAS ALLOWED SURFACE DEWPOINTS TO FALL INTO
THE UPPER 30S IN SOME AREAS...ALTHOUGH LOW 40S ARE PREVALENT.
FOR THIS EVENING/TONIGHT...THE MOST SIGNIFICANT CHANGE WAS TO
COMPLETELY REMOVE ALL MENTION OF SHOWERS/STORMS BEFORE 06Z...AS
MOISTURE RETURN AND RESULTANT ELEVATED INSTABILITY NOW APPEARS
CONSIDERABLY MORE DELAYED THAN IT DID 24 HOURS AGO. THAT BEING
SAID...LATEST RAP-BASED HOURLY MESOANALYSIS INDICATED THE
PRESENCE OF UP TO 500 J/KG MUCAPE CURRENTLY SITTING ACROSS
SOUTHWEST ZONES ALONG THE LEADING EDGE OF MOISTURE RETURN AROUND
700MB. HOWEVER THE 12Z NAM WOULD SUGGEST THIS MUCAPE IS ACTUALLY
MORE MEAGER AND MORE CAPPED THAN THE RAP SUGGESTS...AND GIVEN THE
LIMITED FORCING AND THE FACT THAT A NUMBER OF DETERMINISTIC AND
HIGH RES MODELS SUCH AS THE 12Z 4KM WRF-NMM DO NOT INITIATE
CONVECTION IN THIS AREA THROUGH THIS EVENING...HAVE REMOVED THE
SLIGHT POPS. FOR THE LATE NIGHT 06Z-12Z PERIOD...DECIDED TO BREAK
THE POP/WX GRIDS INTO 3-HOUR BLOCKS...WITH THE PRIMARY FOCUS
SQUARELY ON THE VERY LATE NIGHT/EARLY MORNING HOURS POST-09Z. FOR
THE 06Z-09Z PERIOD...ONLY HAVE SLIGHT POPS CREEPING INTO A FEW FAR
SOUTHWEST COUNTIES. THEN AFTER 09Z...BRING IN 20-30 PERCENT
SHOWER/ISOLATED STORM CHANCES FOR ALL BUT ROUGHLY THE EASTERN 1/4
OF THE CWA. AS THE NIGHT WEARS ON...THE AFOREMENTIONED NORTHWEST
FLOW SHORTWAVE WILL REACH THE SD/NORTHERN NEB BORDER AREA...WHILE
OUT AHEAD OF IT...THETA-E ADVECTION MAINLY IN THE 850-700MB LAYER
WILL BE ON THE INCREASE...AS THE EASTERN EDGE OF A MODEST 850MB
LOW LEVEL JET VEERS INTO THE AREA. INTERESTINGLY...THE NEWLY
ARRIVED 18Z NAM KEEPS MOST ALL OF THIS ACTIVITY OUTSIDE THE CWA
UNTIL AFTER SUNRISE...BUT FEEL AT LEAST 20-30 POPS ARE WARRANTED
BASED ON THE 4KM WRF-NMM AND NSSL 4KM-WRF DEPICTION OF ONE BATCH
OF SHOWERS/FEW STORMS SLIDING INTO THE CWA FROM THE
NORTHWEST...WHILE ANOTHER POTENTIALLY SEPARATE AREA DEVELOPS OVER
THE SOUTHWESTERN CWA MAINLY IN KS. ALTHOUGH NOT ANTICIPATING A
SEVERE WEATHER THREAT THROUGH SUNRISE WITH MUCAPE LIKELY REMAINING
NO MORE THAN A FEW HUNDRED J/KG...SUPPOSE A FEW STRONGER CORES
WITH SMALL HAIL CANNOT BE RULED OUT GIVEN STRONG DEEP LAYER SHEAR
ON THE ORDER OF 50+ KNOTS. TEMP WISE TONIGHT...GIVEN THE SLOWER
ONSET OF CLOUDS AND STORM CHANCES...AND WITH WINDS REMAINING LIGHT
AS THE RIDGE AXIS SLOWLY DEPARTS...NUDGED DOWN LOWS TONIGHT 2-3
DEGREES IN MOST AREAS...WITH MUCH OF THE CWA AIMED INTO THE 50-53
RANGE...AND EVEN COOLER MID-UPPER 40S IN THE FAR EAST...BUT NOT
RECORD-BREAKING TERRITORY.
TURNING TO THE DAYTIME PERIOD 12Z-00Z...SPLIT THE DAY INTO 6-HOUR
BLOCKS FOR POPS/WEATHER...WITH THE OVERALL BEST RAIN CHANCES FOCUSED
DURING THE MORNING. ALOFT...THE COMPACT BUT FAIRLY VIGOROUS
NORTHWEST FLOW WAVE WILL DIVE SOUTHWARD ACROSS THE EASTERN HALF OF
NEBRASKA TOWARD NORTHEAST KANSAS DURING THE DAY...ACCOMPANIED BY
AN ASSOCIATED UPPER LEVEL JET STREAK. ALTHOUGH IT WILL NOT BE AN
ALL-DAY RAIN OUT BY ANY MEANS...THE CONSENSUS OF VARIOUS MODELS
INCLUDING THE 12Z 4KM WRF-NMM REFLECTIVITY SHOWS A DECENT CHANCE
FOR AT LEAST SCATTERED SHOWERS/A FEW STORMS SPREADING SOUTHEAST
ACROSS THE CWA DURING THE DAY...POSSIBLY IN TWO SEPARATE ROUNDS
WITH ONE ROUND DURING THE MORNING...FOLLOWED BY MORE HIT AND MISS
ACTIVITY DURING THE AFTERNOON DIRECTLY UNDER THE SHORTWAVE AXIS.
WITH THE OVERALL BEST COVERAGE EXPECTED DURING THE MORNING
HOURS...INCREASED POPS TO 50S ACROSS ROUGHLY THE NORTHWEST 1/2 OF
THE CWA...BUT KEPT THEM BELOW LIKELY TERRITORY FOR NOW. DURING THE
AFTERNOON...WENT LOWER WITH POPS BUT KEPT AT LEAST 20-30 PERCENT
CHANCES AND HIGHEST ACROSS THE EASTERN 1/2. AS FOR SEVERE
CHANCES...WITH BOTH ELEVATED AND NEAR SURFACE-BASED PARCELS NOT
EXPECTED TO AVERAGE MORE THAN 500 J/KG MOST AREAS...WHICH CAME IN
LOWER ON THE 18Z NAM THAN ITS 12Z RUN...NOT EXPECTING SEVERE
STORMS TO BE A BIG ISSUE. HOWEVER...GIVEN THE VIGOROUS WAVE AND
CONTINUED SEASONABLY STRONG DEEP LAYER SHEAR...AT LEAST A FEW
STRONG TO MARGINALLY SEVERE STORMS MAINLY WITH HAIL POTENTIAL TO
AROUND QUARTER SIZE ARE NOT OUT OF THE QUESTION...ESPECIALLY IN
KANSAS ZONES...AND AGREE WITH SPC ON HIGHLIGHTING THESE SOUTHERN
ZONES FOR 5 PERCENT SEVERE PROBS ON THE DAY 2 OUTLOOK. AS FOR RAIN
AMOUNTS SATURDAY...WOULD EXPECT THAT MOST PLACES WILL AVERAGE
UNDER ONE-QUARTER INCH...SO NOT A MAJOR BOOST TO DROUGHT RELIEF BY
ANY MEANS. TEMP-WISE...IT WILL BE A TRICKY BATTLE BETWEEN
WIDESPREAD CLOUDS/SCATTERED RAIN FOR THE MAJORITY OF THE DAY...BUT
POTENTIAL FOR DECENT AFTERNOON CLEARING ESPECIALLY NORTHWEST.
OVERALL MADE NO BIG CHANGES...BUT RAISED WESTERN ZONES A FEW
DEGREES...ESPECIALLY UP AROUND ORD. HAVE MOST OF THE CWA TOPPING
OUT IN THE 76-81 RANGE.
.LONG TERM...STARTING SATURDAY EVENING. GUIDANCE SUGGESTS
NORTHWESTERLY UPPER LEVEL FLOW WILL PERSIST OVER THE CENTRAL
PLAINS THROUGH MUCH OF THE EXTENDED FORECAST PERIOD AS UPPER LEVEL
RIDGING REMAINS RELEGATED TO THE SOUTHWESTERN CONUS. QPF FIELDS
FROM THE SREF- MEAN...NAM AND OPERATIONAL GFS SUGGEST LINGERING
PRECIPITATION WILL BE POSSIBLE OVER OUR SOUTHEASTERN CWA 00Z-06Z
SUNDAY AS A MID LEVEL SHORT WAVE DEPARTS THE AREA. AS A
RESULT...WENT AHEAD AND KEPT 20% POPS GOING ACROSS OUR SOUTHEAST
00Z-06Z SUNDAY. A FEW SMALL-SCALE MID LEVEL PERTURBATIONS COULD
POTENTIALLY PUSH OVER THE CENTRAL PLAINS SUNDAY AND MONDAY.
DESPITE THE POSSIBILITY OF THESE SMALL-SCALE DISTURBANCES...OPTED
TO KEEP THE CWA DRY DURING THIS TIME PERIOD GIVEN THE VERY LOW
PROBABILITY OF PRECIPITATION ACTUALLY BEING REALIZED FROM ANY ONE
OF THESE FEATURES. THE EC...OPERATIONAL GFS AND GEFS-MEAN ALL
ADVERTISE A MORE SIGNIFICANT MID LEVEL SHORT WAVE WILL PUSH
SOUTHEAST ACROSS THE CENTRAL HIGH PLAINS MONDAY NIGHT INTO
TUESDAY. AT THIS TIME IT APPEARS THE BULK OF THE DPVA AND MID
LEVEL THERMAL ADVECTION WILL REMAIN SOUTHWEST OF OUR AREA...BUT
THERE MAY BE JUST ENOUGH OMEGA FOR PRECIPITATION ACROSS OUR
WEST/SOUTHWEST AND AS A RESULT...WENT AHEAD AND KEPT 20%-30% POPS
GOING ACROSS OUR WEST/SOUTHWEST FOR MONDAY NIGHT. SOME OF THIS
OMEGA MAY CREEP A BIT FARTHER EAST INTO OUR AREA DURING THE DAY
TUESDAY SO WENT AHEAD AND SPREAD POPS A BIT FARTHER EAST ACROSS
THE CWA DURING THE DAY TUESDAY AS A RESULT. AN OVERALL LACK IN
KINEMATIC FORCING SHOULD THEN PRESENT DRY CONDITIONS TO OUR AREA
TUESDAY NIGHT THROUGH THURSDAY...WITH GUIDANCE SUGGESTING YET
ANOTHER MID LEVEL SHORT WAVE WILL BRING PRECIPITATION CHANCES TO
MUCH OF THE AREA THURSDAY NIGHT INTO FRIDAY.
VERY LITTLE CHANGE IN THE LOW LEVEL AIRMASS SUGGESTS TEMPERATURES
SUNDAY THROUGH FRIDAY WILL BE FAIRLY SIMILAR...WITH PERHAPS A SLIGHT
WARMING TREND TOWARDS THE END OF THE FORECAST PERIOD. GIVEN
THIS...BELOW-NORMAL TEMPERATURES ARE FORECAST ACROSS THE CWA SUNDAY
WITH HIGHS IN THE UPPER 70S AND LOWS IN THE UPPER 40S TO NEAR 50.
SLIGHTLY WARMER BUT STILL BELOW-NORMAL TEMPERATURES ARE THEN
FORECAST FOR MUCH OF THE CWA MONDAY BEFORE WEAK LOW LEVEL WARM
ADVECTION PROVIDES NEAR TO SLIGHTLY ABOVE-NORMAL TEMPERATURES
TUESDAY ONWARD.
&&
.PREV DISCUSSION... /ISSUED 1217 PM CDT FRI AUG 17 2012/
AVIATION...18Z KGRI TAF. VFR CEILING/VISIBILITY IS FORECAST
THROUGH THE NEXT 24 HOURS...WITH THE MAIN CONCERN BEING A RISK FOR
SHOWERS/WEAK THUNDERSTORMS DURING PARTS OF THE FINAL 6 HOURS OF
THE PERIOD MAINLY SATURDAY MORNING. PRIOR TO THIS PRECIPITATION
POSSIBILITY...THE REST OF TODAY AND THROUGH TONIGHT WILL FEATURE
LIGHT/GENERALLY VARIABLE BREEZES AS A SURFACE HIGH PRESSURE AXIS
DEPARTS...ALONG WITH AT MOST A SMATTERING OF MID LEVEL CLOUD
COVER. FOR NOW...DECIDED TO GO WITH A PROB30 -TSRA MENTION FROM
12Z-18Z TO COVER THE THUNDERSTORM RISK...AND WILL DEFER TO LATER
FORECASTS TO INSERT POSSIBLE TEMPO/PREVAILING GROUPS AS THE EVENT
NEARS AND TIMING CONFIDENCE INCREASES. EVEN DURING POSSIBLE
THUNDERSTORM ACTIVITY...DO NOT FORESEE CEILING DROPPING EVEN CLOSE
TO MVFR THRESHOLDS...AND VISIBILITY SHOULD REMAIN VFR AS WELL
UNLESS A BRIEF HEAVY RAIN CORE SLIDES THROUGH.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/AVIATION...PFANNKUCH
LONG TERM...BRYANT
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
1140 PM MDT THU AUG 16 2012
.AVIATION...
06Z TAF CYCLE
WHILE VFR CONDITIONS WILL PREVAIL IN MOST LOCALES OF NORTHERN AND
CENTRAL NEW MEXICO...BATCHES OF REMNANT THUNDERSTORMS WILL PRODUCE
BRIEF AND LOCALIZED DOWNPOURS REDUCING VISIBILITIES AND CEILINGS
TEMPORARILY TO MVFR CONDITIONS. COVERAGE HAS DWINDLED
SIGNIFICANTLY...BUT STORMS WILL CONTINUE TO IMPACT CENTRAL
HIGHLANDS AND A NEW BATCH OF STORMS COULD ROLL OFF OF THE NORTHERN
MOUNTAINS AND INTO THE CENTRAL HIGHLANDS AND EAST CENTRAL PLAINS
BEFORE DAWN FRIDAY. GUSTY AND ERRATIC WINDS AND SMALL HAIL WILL
ALSO ACCOMPANY THE DOWNPOURS. ANOTHER ACTIVE AFTERNOON/EVENING IS
ANTICIPATED ON FRIDAY WITH STORMS FAVORING THE CENTRAL MOUNTAIN
CHAIN AND ADJACENT HIGH PLAINS...AS WELL AS PARTS OF THE
SOUTHWESTERN MOUNTAINS.
52
&&
.PREV DISCUSSION...913 PM MDT THU AUG 16 2012...
QUICK ZFP UPDATE JUST SENT. ADJUSTED WINDS IN THE MIDDLE/LOWER RIO
GRANDE VALLEY DUE TO GUSTS TO AROUND 35 MPH CONTINUING AT THE
SUNPORT THIS EVENING. ALSO TRIMMED OVERNIGHT POPS BACK AS
CONVECTION STARTING TO WANE.
.PREV DISCUSSION...323 PM MDT THU AUG 16 2012...
DEFINITE INCREASE IN STORM STRENGTH AND COVERAGE TODAY AS EXPECTED
WITH SEVERAL FORCING MECHANISMS IN PLACE OVER THE STATE. CIRA BLENDED
PWAT IMAGERY SHOWING VALUES OF 100-125 PCT OF NORMAL. THE AXIS OF THE
H5 RIDGE IS POSITIONED FROM NORTHERN AZ SOUTHEAST ACROSS WEST CENTRAL
NM. H5 TEMPS OF -6 TO -7C ARE HELPING NOT TO CAP ANY CONVECTION AS
HAS BEEN THE CASE. WINDS ARE ALSO VERY WEAK ABOVE 700MB SO COMBINATION
OF HIGHER MOISTURE...COOLER TEMPS ALOFT...AND GOOD SURFACE HEATING WILL
ALLOW FOR LOCALLY HEAVY RAINFALL THRU THIS EVENING. THE HRRR AND RUC
MODELS INDICATE CONVECTION WILL ORGANIZE INTO THE MIDDLE RIO GRANDE
VALLEY SOUTHEASTWARD SO HAVE RAISED POPS TO HIGH CHANCE AND LIKELY.
DID NOT HAVE HIGH ENOUGH CONFIDENCE TO PLACE LOCALLY HEAVY RAINFALL
WORDING IN FORECAST FOR TONIGHT...AND FOR THAT MATTER THE NEXT FEW
DAYS...AS IT WILL BE HARD TO PINPOINT ANY SPECIFIC AREA FOR ENHANCED
THREAT.
THE H5 RIDGE AXIS WILL CHANGE LITTLE OVER THE NEXT FEW DAYS...SETTING
UP WEAK STEERING FLOW FOR CENTRAL AND WESTERN NM WHILE THE EAST ENJOYS
THE BENEFITS OF NW FLOW ALOFT. LIGHT UPSLOPE FLOW ACROSS THE PLAINS
ONTO THE EAST SLOPES BENEATH NW FLOW WILL BE FAVORABLE FOR POTENTIALLY
SOME OF BEST PRECIP SEEN IN QUITE SOME TIME. ANOTHER BACK DOOR FRONT
SUNDAY WILL JUST ENHANCE MOISTURE AND PRECIP CHANCES AGAIN. RAISED
POPS EVEN MORE TO THE HIGH CHANCE/LIKELY CATEGORY THRU THE WEEKEND.
TEMPS WILL BE MUCH CLOSER TO NORMAL AND EVEN A FEW DEGREES BELOW. GAP
WINDS ARE EXPECTED AGAIN IN THE RIO GRANDE VALLEY SATURDAY EVENING
INTO SUNDAY MORNING.
MODELS REMAIN AT ODDS BEYOND THE WEEKEND WITH HOW MUCH CONDITIONS WILL
DRY OUT. THE GFS HAS THE RIDGE SLIDING EAST AND CENTERING OVER CENTRAL
NM MONDAY THRU MOST OF NEXT WEEK...WHILE THE ECMWF KEEPS THE RIDGE TO
THE WEST AND FORCING MORE BACK DOOR FRONTS INTO THE AREA. GIVEN THE
PATTERN THIS SUMMER WILL BE FAVORING THE ECMWF AT THIS TIME...WHICH
WILL KEEP TEMPS NEAR NORMAL AND PRECIP CHANCES PERHAPS AT CLIMO FOR
LATE AUGUST. GUYER
.FIRE WEATHER...
CRITICAL FIRE WEATHER...NOT EXPECTED THROUGH AT LEAST MIDWEEK NEXT
WEEK.
FCST MODELS REMAIN IN FAIRLY GOOD AGREEMENT ON GENERAL FCST PATTERN
THROUGH THE START TO MIDDLE OF NEXT WEEK. UPPER HIGH CENTER TO
CONTINUE TO MEANDER BACK AND FORTH GENERALLY BETWEEN NV AND AZ. THIS
WILL ALLOW FOR SOME WEAK TO MODERATE LOW LVL MOISTURE REPLENISHMENT
FROM THE E THROUGH S FROM TIME TO TIME WITH COMBINATION OF WESTBOUND
THROUGH NORTHBOUND OUTFLOWS FROM STORM COMPLEXES IN S AND E HALVES
OF THE STATE AS WELL AS CURRENT WEAKENING BACK DOOR FRONT VCNTY OF
RIO GRANDE VALLEY AS OF THIS WRITING AND ANOTHER ONE DUE INTO E AND
PERHAPS CENTRAL NM OVER THE WEEKEND.
SHOWERS AND STORMS THIS EVE AND OVERNIGHT TO BE MOST NUMEROUS...AND
WITH GOOD WETTING FOOTPRINTS...TO E OF THE CONTINENTAL DIVIDE WITH
MOST LIGHTNING OVER WITH BY OR NOT TOO LONGER AFTER MIDNIGHT...
ESPECIALLY HIGHER TERRAIN. GOOD TO EXCELLENT HUMIDITY RECOVERIES
OVERNIGHT.
FOR FRIDAY...ACTIVE CONVECTION EXPECTED ACROSS THE STATE...WITH
WETTING RAINS THE BEST BET AGAIN E OF DIVIDE. MINIMUM HUMIDITIES
INCREASING TO THE HIGH 20S TO THE MID 40S PCT RANGE OVER MUCH OF THE
STATE...WITH SOME HIGH TEENS AND 20S PCT REMAINING OVER THE DRYER
NORTHWEST QUADRANT. AGAIN GOOD TO EXCELLENT HUMIDITY RECOVERY
OVERNIGHT.
SATURDAY WILL BRING WEAK COLD FRONT INTO THE NORTHEAST PLAINS...
PROGRESSING TO THE S AND W LATER IN THE DAY THROUGH SUN AM. WETTING
RAINS MOST LIKELY ALONG AND E THROUGH N OF FRONTAL BOUNDARY. NW
PLATEAU STILL GETTING THE SHORT END OF THE STICK WITH REGARDS TO
CONVECTION AND WETTING RAIN. VERY GOOD TO EXCELLENT RECOVERIES
OVERNIGHT FOR ALL BUT THE NORTHWEST...WHERE RECOVERY WILL DROP BACK
INTO THE GOOD CATEGORY. FOR SUN THROUGH TUE THE UPPER HIGH AND RIDGE
STILL GENERALLY TO W OF NM. PRETTY GOOD CHANCES FOR WETTING RAINS
SUNDAY BUT BEGINNING A BIT OF A DOWNTURN MON AND TUE. AFTN TEMPS
SHOULD WARM A FEW DEGREES MOST AREAS BY MON OR TUE AND THIS WILL
LOWER MIN HUMIDITIES AND LESSEN OVERNIGHT RECOVERIES. 43
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
134 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO MOVE ACROSS NEW YORK THIS AFTERNOON.
FOLLOWING THE FRONT EXPECT COOLER TEMPERATURES AND LESS HUMID
CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE COLD FRONT HAS CROSSED PRETTY MUCH ALL OF THE CWA WITH SOME
LINGERING SHOWERS ACROSS THE SOUTHEAST SECTIONS.
WITH COOLER AIR MOVING IN BEHIND THE FRONT...AND THE RELATIVELY
WARM LAKES...EXPECT ANY BRIEF CLEARING WILL LIKELY FILL IN WITH
LAKE-AIDED STRATOCUMULUS THIS AFTERNOON. THE HRRR HAS CONSISTENTLY
DEVELOPED SHOWERS AS A SW FLOW OFF LAKE ERIE CONVERGES WITH A MORE
WNW FLOW. FEEL THIS IS A REAL POSSIBILITY...SO WILL CARRY A CHANCE
FOR SHOWERS CENTERED IN THE NORTHTOWNS WHERE THIS CONVERGENCE
TYPICALLY OCCURS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
THE COLD FRONT HAS MOVED THROUGH ALL OF THE TAF SITES AND
CONTINUES TO MOVE TO THE EAST OF THE CWA. VFR CONDS BEHIND THE
FRONT WILL OCNLY LOWER TO MVFR AS A FAIR AMOUNT OF CU DEVELOPS IN
THE SELF-DESTRUCTIVE SUNSHINE. THERE MAY BE A FEW STRAY SHOWERS IN
THE KIAG-KBUF VCNTY ALONG THE LAKE ERIE / LAKE ONTARIO LAKE
CONVERGENCE BOUNDARY.
CLOUDS SHOULD SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES
DIMINISH...AND DRIER AIR MOVES IN. AS COOL AIR BUILDS IN ALOFT
EXPECT SOME LAKE CLOUDS TO DEVELOP SOUTHWEST OF LAKES ERIE AND
ONTARIO PRODUCING LOCALIZED MVFR CIGS. THERE COULD BE SOME FOG IN
JHW...OTHERWISE EXPECT VFR CONDITIONS TONIGHT.
OUTLOOK...
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY AND WEDNESDAY...VFR.
&&
.MARINE...
THE COLD FRONT HAS CROSSED THE LAKES WITH A WEST TO NORTHWEST FLOW
ESTABLISHING ITSELF ACROSS THE LAKES.
THE BRISK FLOW WILL PRODUCE WAVES INCREASING TO 5 FT ACROSS THE
EASTERN LAKE ONTARIO REGION. SMALL CRAFT ADVISORIES HAVE BEEN
POSTED THROUGH THE EARLY OVERNIGHT FOR THESE AREAS.
AS THE SURFACE HIGH BUILDS ACROSS THE REGION OVERNIGHT AND
SATURDAY WINDS WILL DIMINISH.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LEZ040-
041.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR
LOZ044-045.
&&
$$
SYNOPSIS...APFFEL/LEVAN
NEAR TERM...APFFEL/LEVAN
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...LEVAN
MARINE...LEVAN
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1139 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO MOVE ACROSS NEW YORK THIS AFTERNOON.
FOLLOWING THE FRONT EXPECT COOLER TEMPERATURES AND LESS HUMID
CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE COLD FRONT HAS CROSSED PRETTY MUCH ALL OF THE CWA WITH SOME
LINGERING SHOWERS ACROSS THE SOUTHEAST SECTIONS.
WITH COOLER AIR MOVING IN BEHIND THE FRONT...AND THE RELATIVELY
WARM LAKES...EXPECT ANY BRIEF CLEARING WILL LIKELY FILL IN WITH
LAKE-AIDED STRATOCUMULUS THIS AFTERNOON. THE HRRR HAS CONSISTENTLY
DEVELOPED SHOWERS AS A SW FLOW OFF LAKE ERIE CONVERGES WITH A MORE
WNW FLOW. FEEL THIS IS A REAL POSSIBILITY...SO WILL CARRY A CHANCE
FOR SHOWERS CENTERED IN THE NORTHTOWNS WHERE THIS CONVERGENCE
TYPICALLY OCCURS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
THE COLD FRONT HAS MOVED THROUGH ALL OF THE TAF SITES AND
CONTINUES TO MOVE TO THE EAST OF THE CWA. VFR CONDS BEHIND THE
FRONT WILL LOWER TO MVFR AS A FAIR AMOUNT OF CU DEVELOPS IN THE
SELF-DESTRUCTIVE SUNSHINE. THERE MAY BE A STRAY SHOWERS IN THE
VICINITY OF BUF THIS AFTERNOON DUE TO THE CONVERGENCE OF A SW FLOW
UP LAKE ERIE AND A WNW FLOW ELSEWHERE.
CLOUDS SHOULD SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES
DIMINISH...AND DRIER AIR MOVES IN. THERE COULD BE SOME FOG IN
JHW...OTHERWISE EXPECT VFR CONDITIONS TONIGHT.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY AND WEDNESDAY...VFR.
&&
.MARINE...
THE COLD FRONT HAS CROSSED THE LAKES WITH A WEST TO NORTHWEST FLOW
ESTABLISHING ITSELF ACROSS THE LAKES.
THE BRISK FLOW WILL PRODUCE WAVES INCREASING TO 5 FT ACROSS THE
EASTERN LAKE ONTARIO REGION. SMALL CRAFT ADVISORIES HAVE BEEN
POSTED THROUGH THE EARLY OVERNIGHT FOR THESE AREAS.
AS THE SURFACE HIGH BUILDS ACROSS THE REGION OVERNIGHT AND
SATURDAY WINDS WILL DIMINISH.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LEZ040-
041.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR
LOZ044-045.
&&
$$
SYNOPSIS...APFFEL/LEVAN
NEAR TERM...APFFEL/LEVAN
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL/LEVAN
MARINE...APFFEL/LEVAN
AREA FORECAST DISCUSSION
NWS BUFFALO NY
942 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE REGION THROUGH THIS MORNING
PRODUCING A BAND OF SHOWERS AND POSSIBLY A THUNDERSTORM. FOLLOWING
THE PASSAGE OF THE COLD FRONT EXPECT COOLER TEMPERATURES AND LESS
HUMID CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE COLD FRONT CONTINUES TO MOVE ACROSS THE AREA THIS MORNING.
ACTIVITY ALONG THE FRONT IS CERTAINLY NOT AS HEAVY AS EARLIER THIS
MORNING WITH LITTLE THUNDER AT THIS TIME.
THE FRONT WILL EXIT TO THE EAST BY THIS AFTERNOON...WHICH WILL END
THE STEADY RAIN SHOWERS. HOWEVER...WITH COOLER AIR MOVING IN BEHIND
THE FRONT...AND THE RELATIVELY WARM LAKES...EXPECT ANY BRIEF
CLEARING WILL LIKELY FILL IN WITH LAKE-AIDED STRATOCUMULUS THIS
AFTERNOON. THE HRRR HAS CONSISTENTLY DEVELOPED SHOWERS AS A SW FLOW
OFF LAKE ERIE CONVERGES WITH A MORE WNW FLOW. FEEL THIS IS A REAL
POSSIBILITY...SO WILL CARRY A CHANCE FOR SHOWERS CENTERED IN THE
NORTHTOWNS WHERE THIS CONVERGENCE TYPICALLY OCCURS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
A COLD FRONT WHICH HAS JUST REACHED IAG/BUF/JHW THROUGH 12Z WILL
CONTINUE TO PUSH QUICKLY TO THE EAST. SHOWS WILL LINGER BRIEFLY
BEHIND THE BOUNDARY THIS MORNING...BUT SHOULD GIVE WAY TO FAIR
WEATHER. EVEN WITH THE SHOWERS...EXPECT MVFR/VFR CONDITIONS. THERE
IS STILL A CHANCE FOR THUNDERSTORMS...MAINLY AT ART WHICH IS STILL
AHEAD OF THE FRONT. THUNDERSTORMS MAY BRIEFLY DROP VSBY TO 2SM OR
LESS.
FOLLOWING THE PASSAGE OF THE COLD FRONT EXPECT THE VFR
LEVEL DECK TO TEMPORARILY SCATTER OUT THIS MORNING...ONLY TO FILL
BACK IN AGAIN WITH DAYTIME HEATING AS MOISTURE BECOMES TRAPPED
BENEATH THE SUBSIDENCE INVERSION. EXPECT MOST IF NOT ALL OF THIS
POST-FRONTAL CLOUD COVER TO BE VFR IN THE 035-050 KFT RANGE. THERE
MAY BE A STRAY SHOWERS IN THE VICINITY OF BUF THIS AFTERNOON DUE
TO THE CONVERGENCE OF A SW FLOW UP LAKE ERIE AND A WNW FLOW ELSEWHERE.
CLOUDS SHOULD SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES
DIMINISH...AND DRIER AIR MOVES IN. THERE COULD BE SOME FOG IN
JHW...OTHERWISE EXPECT VFR CONDITIONS TONIGHT.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY...VFR.
&&
.MARINE...
A COLD FRONT WILL MOVE ACROSS THE WATERS FROM WEST TO EAST THIS
MORNING. WINDS WILL BRIEFLY BE BREEZY AHEAD OF THE FRONT...BUT THE
SSW WIND DIRECTION IS UNFAVORABLE FOR BUILDING WAVES ON LAKE
ONTARIO. DO HAVE SOME CONCERN ON LAKE ERIE...WHERE A QUICK SHIFT TO
THE NW BEHIND THE THE FRONT EARLY THIS MORNING WILL LIKELY RESULT IN
A FEW HOURS OF CHOPPY CONDITIONS. SMALL CRAFT ADVISORY WILL BE
CONTINUED THROUGH EARLY AFTERNOON FOR THIS REASON.
RECD A REPORT OF SEVERAL WATERSPOUTS ACCOMPANYING THE FRONT OVER
LAKE ERIE EARLIER THIS MORNING SO WILL INCLUDE A CHANCE OF A
WATERSPOUT FOR EASTERN LAKES ERIE AND ONTARIO THROUGH EARLY
AFTERNOON.
THIS AFTERNOON...WINDS WILL SHIFT TO THE WNW BEHIND THE FRONT.
THIS FLOW WILL PERSIST...AND WILL LIKELY PRODUCE WAVES TO 5 FT ON
EASTERN PORTIONS OF LAKE ONTARIO MID-AFTERNOON ONWARD. WINDS WILL
GRADUALLY DIMINISH LATE TONIGHT.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM
EDT SATURDAY FOR LOZ044-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/LEVAN
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL/LEVAN
AREA FORECAST DISCUSSION
NWS BUFFALO NY
721 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE REGION THROUGH THIS MORNING
PRODUCING A BAND OF SHOWERS AND POSSIBLY A THUNDERSTORM. FOLLOWING
THE PASSAGE OF THE COLD FRONT EXPECT COOLER TEMPERATURES AND LESS
HUMID CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT DAYBREAK...A COLD FRONTAL BOUNDARY EXTENDED ALONG A JAMESTOWN TO
BUFFALO LINE. THERE ARE TWO AREAS OF SHOWERS ASSOCIATED WITH
THIS FRONT...THE FIRST OUT AHEAD OF THE FRONT...AND A SECOND JUST
BEHIND THE WIND SHIFT. SHOWERS WILL MOVE EASTWARD WITH THE FRONT.
WHILE MOST LOCATIONS WILL RECEIVE SOME RAINFALL FROM THE
FRONT...IT WILL VARY BY LOCATION...WITH HEAVIEST RAINS LIKELY
SOUTH OF BUFFALO...AND ALSO EAST OF LAKE ONTARIO. THE COMMON
FACTOR WITH THESE TWO LOCATIONS IS THAT LAKE MOISTURE IS ABLE TO
ENHANCE SHOWERS WITH THE FRONT. WHILE A THUNDERSTORM CAN/T BE
RULED OUT THROUGH THIS MORNING...THE CHANCE APPEARS TO BE
DIMINISHING AS SHOWERS WORK EASTWARD AWAY FROM THE MOISTURE OF
LAKE ERIE.
THE FRONT WILL EXIT TO THE EAST BY THIS AFTERNOON...WHICH WILL END
THE STEADY RAIN SHOWERS. HOWEVER...WITH COOLER AIR MOVING IN BEHIND
THE FRONT...AND THE RELATIVELY WARM LAKES...EXPECT ANY BRIEF
CLEARING WILL LIKELY FILL IN WITH LAKE-AIDED STRATOCUMULUS THIS
AFTERNOON. THE HRRR HAS CONSISTENTLY DEVELOPED SHOWERS AS A SW FLOW
OFF LAKE ERIE CONVERGES WITH A MORE WNW FLOW. FEEL THIS IS A REAL
POSSIBILITY...SO WILL CARRY A CHANCE FOR SHOWERS CENTERED IN THE
NORTHTOWNS WHERE THIS CONVERGENCE TYPICALLY OCCURS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A COLD FRONT WHICH HAS JUST REACHED IAG/BUF/JHW THROUGH 12Z WILL
CONTINUE TO PUSH QUICKLY TO THE EAST. SHOWS WILL LINGER BRIEFLY
BEHIND THE BOUNDARY THIS MORNING...BUT SHOULD GIVE WAY TO FAIR
WEATHER. EVEN WITH THE SHOWERS...EXPECT MVFR/VFR CONDITIONS. THERE
IS STILL A CHANCE FOR THUNDERSTORMS...MAINLY AT ART WHICH IS STILL
AHEAD OF THE FRONT. THUNDERSTORMS MAY BRIEFLY DROP VSBY TO 2SM OR
LESS.
FOLLOWING THE PASSAGE OF THE COLD FRONT EXPECT THE VFR
LEVEL DECK TO TEMPORARILY SCATTER OUT THIS MORNING...ONLY TO FILL
BACK IN AGAIN WITH DAYTIME HEATING AS MOISTURE BECOMES TRAPPED
BENEATH THE SUBSIDENCE INVERSION. EXPECT MOST IF NOT ALL OF THIS
POST-FRONTAL CLOUD COVER TO BE VFR IN THE 035-050 KFT RANGE. THERE
MAY BE A STRAY SHOWERS IN THE VICINITY OF BUF THIS AFTERNOON DUE
TO THE CONVERGENCE OF A SW FLOW UP LAKE ERIE AND A WNW FLOW ELSEWHERE.
CLOUDS SHOULD SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES
DIMINISH...AND DRIER AIR MOVES IN. THERE COULD BE SOME FOG IN
JHW...OTHERWISE EXPECT VFR CONDITIONS TONIGHT.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY...VFR.
&&
.MARINE...
A COLD FRONT WILL MOVE ACROSS THE WATERS FROM WEST TO EAST THIS
MORNING. WINDS WILL BRIEFLY BE BREEZY AHEAD OF THE FRONT...BUT THE
SSW WIND DIRECTION IS UNFAVORABLE FOR BUILDING WAVES ON LAKE
ONTARIO. DO HAVE SOME CONCERN ON LAKE ERIE...WHERE A QUICK SHIFT TO
THE NW BEHIND THE THE FRONT EARLY THIS MORNING WILL LIKELY RESULT IN
A FEW HOURS OF CHOPPY CONDITIONS. BECAUSE OF THIS WILL ISSUE A BRIEF
SMALL CRAFT ADVISORY FOR LAKE ERIE THROUGH LATE MORNING.
WITH SHOWERS AND THUNDERSTORMS MOVING ACROSS THE LAKES THROUGH THIS
MORNING...AN ISOLATED WATERSPOUT CANNOT BE RULED OUT. THIS
SAID...TEMPERATURES ALOFT ARE NOT AS COLD AS A FEW DAYS AGO...SO ANY
ACTIVITY SHOULD NOT BE AS NEARLY WIDESPREAD.
THIS AFTERNOON...WINDS WILL SHIFT TO THE WNW BEHIND THE FRONT. THIS
FLOW WILL PERSIST...AND WILL LIKELY PRODUCE WAVES TO 5 FT ON EASTERN
PORTIONS OF LAKE ONTARIO MID-AFTERNOON ONWARD. WINDS WILL GRADUALLY
DIMINISH LATE TONIGHT.
FINE BOATING CONDITIONS ARE THEN EXPECTED FOR THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM
EDT SATURDAY FOR LOZ044-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
645 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE REGION THROUGH THIS MORNING
PRODUCING A BAND OF SHOWERS AND POSSIBLY A THUNDERSTORM. FOLLOWING
THE PASSAGE OF THE COLD FRONT EXPECT COOLER TEMPERATURES AND LESS
HUMID CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT DAYBREAK...A COLD FRONTAL BOUNDARY EXTENDED ALONG A JAMESTOWN TO
BUFFALO LINE. THERE ARE TWO AREAS OF SHOWERS ASSOCIATED WITH
THIS FRONT...THE FIRST OUT AHEAD OF THE FRONT...AND A SECOND JUST
BEHIND THE WIND SHIFT. SHOWERS WILL MOVE EASTWARD WITH THE FRONT.
WHILE MOST LOCATIONS WILL RECEIVE SOME RAINFALL FROM THE
FRONT...IT WILL VARY BY LOCATION...WITH HEAVIEST RAINS LIKELY
SOUTH OF BUFFALO...AND ALSO EAST OF LAKE ONTARIO. THE COMMON
FACTOR WITH THESE TWO LOCATIONS IS THAT LAKE MOISTURE IS ABLE TO
ENHANCE SHOWERS WITH THE FRONT. WHILE A THUNDERSTORM CAN/T BE
RULED OUT THROUGH THIS MORNING...THE CHANCE APPEARS TO BE
DIMINISHING AS SHOWERS WORK EASTWARD AWAY FROM THE MOISTURE OF
LAKE ERIE.
THE FRONT WILL EXIT TO THE EAST BY THIS AFTERNOON...WHICH WILL END
THE STEADY RAIN SHOWERS. HOWEVER...WITH COOLER AIR MOVING IN BEHIND
THE FRONT...AND THE RELATIVELY WARM LAKES...EXPECT ANY BRIEF
CLEARING WILL LIKELY FILL IN WITH LAKE-AIDED STRATOCUMULUS THIS
AFTERNOON. THE HRRR HAS CONSISTENTLY DEVELOPED SHOWERS AS A SW FLOW
OFF LAKE ERIE CONVERGES WITH A MORE WNW FLOW. FEEL THIS IS A REAL
POSSIBILITY...SO WILL CARRY A CHANCE FOR SHOWERS CENTERED IN THE
NORTHTOWNS WHERE THIS CONVERGENCE TYPICALLY OCCURRS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
THROUGH 09Z...RADAR SHOWS A FAIRLY SOLID LINE OF SHOWERS WITH
EMBEDDED THUNDERSTORMS ACROSS AND JUST EAST OF LAKE ERIE. THIS
WILL BRING A PERIOD OF RAIN TO TAF SITES...AND PERHAPS A
THUNDERSTORM. CONDITIONS SHOULD MAINLY BE VFR OUTSIDE OF HEAVIER
RAIN SHOWERS WHICH MAY BRIEFLY LOWER VSBY TO AROUND 2SM.
FOLLOWING THE PASSAGE OF THE COLD FRONT EXPECT THE VFR LEVEL DECK TO
TEMPORARILY SCATTER OUT FRIDAY MORNING...ONLY TO FILL BACK IN AGAIN
WITH DAYTIME HEATING AS MOISTURE BECOMES TRAPPED BENEATH THE
SUBSIDENCE INVERSION. EXPECT MOST IF NOT ALL OF THIS POST-FRONTAL
CLOUD COVER TO BE VFR IN THE 035-050 KFT RANGE. THIS DECK SHOULD
SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES DIMINISH...AND
DRIER AIR MOVES IN.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY...VFR.
&&
.MARINE...
A COLD FRONT WILL MOVE ACROSS THE WATERS FROM WEST TO EAST THIS
MORNING. WINDS WILL BRIEFLY BE BREEZY AHEAD OF THE FRONT...BUT THE
SSW WIND DIRECTION IS UNFAVORABLE FOR BUILDING WAVES ON LAKE
ONTARIO. DO HAVE SOME CONCERN ON LAKE ERIE...WHERE A QUICK SHIFT TO
THE NW BEHIND THE THE FRONT EARLY THIS MORNING WILL LIKELY RESULT IN
A FEW HOURS OF CHOPPY CONDITIONS. BECAUSE OF THIS WILL ISSUE A BRIEF
SMALL CRAFT ADVISORY FOR LAKE ERIE THROUGH LATE MORNING.
WITH SHOWERS AND THUNDERSTORMS MOVING ACROSS THE LAKES THROUGH THIS
MORNING...AN ISOLATED WATERSPOUT CANNOT BE RULED OUT. THIS
SAID...TEMPERATURES ALOFT ARE NOT AS COLD AS A FEW DAYS AGO...SO ANY
ACTIVITY SHOULD NOT BE AS NEARLY WIDESPREAD.
THIS AFTERNOON...WINDS WILL SHIFT TO THE WNW BEHIND THE FRONT. THIS
FLOW WILL PERSIST...AND WILL LIKELY PRODUCE WAVES TO 5 FT ON EASTERN
PORTIONS OF LAKE ONTARIO MID-AFTERNOON ONWARD. WINDS WILL GRADUALLY
DIMINISH LATE TONIGHT.
FINE BOATING CONDITIONS ARE THEN EXPECTED FOR THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM
EDT SATURDAY FOR LOZ044-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
514 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE REGION THROUGH THIS MORNING
PRODUCING A BAND OF SHOWERS AND POSSIBLY A THUNDERSTORM. FOLLOWING
THE PASSAGE OF THE COLD FRONT EXPECT COOLER TEMPERATURES AND LESS
HUMID CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE MAIN FORECAST CHALLENGE FOR TODAY IS HOW WIDESPREAD RAINFALL
WILL BE WITH THE FRONTAL PASSAGE THIS MORNING. THROUGH 500
AM...RADAR SHOWS A FAIRLY SOLID LINE OF SHOWERS WITH EMBEDDED
THUNDERSTORMS ACROSS AND JUST EAST OF LAKE ERIE. MODEL GUIDANCE
IS CONSISTENT IN EXPANDING THIS AREA OF SHOWERS AS IT MOVES ACROSS
WESTERN NEW YORK...AND A ROUND OF SHOWERS APPEARS LIKELY FOR THE REGION.
THE 00Z GFS/AND 04Z HRRR HAD A FAIRLY GOOD HANDLE ON THE UPSTREAM
MCS...AND HAVE HAD A GOOD HANDLE ON SHOWER DEVELOPMENT ON LAKE
ERIE SO FAR. THESE STILL SUGGEST THAT SHOWERS WILL LIKELY
ACCOMPANY THE FRONT EARLY THIS...WITH STEADIEST RAIN SHOWERS
BUFFALO SOUTHWARD AS WINDS SHIFTING TO THE NORTHWEST SWEEP
MOISTURE FROM LAKE ERIE INTO WESTERN PORTIONS OF THE SOUTHERN
TIER. THE FRONTAL WILL BRING A COUPLE HOURS OF SHOWERS TO
MOST...WITH QPFS MAINLY ON THE LIGHT SIDE...LESS THAN A TENTH OF
AN INCH. LOOK FOR A BIT MORE THAN THIS BUFFALO SOUTHWARD...WHERE A
BLEND OF THE GFS/HRRR FORECAST AROUND A QUARTER INCH OF RAIN.
THE FRONT WILL EXIT TO THE EAST BY THIS AFTERNOON...WHICH WILL END
THE STEADY RAIN SHOWERS. HOWEVER...WITH COOLER AIR MOVING IN BEHIND
THE FRONT...AND THE RELATIVELY WARM LAKES...EXPECT ANY BRIEF
CLEARING WILL LIKELY FILL IN WITH LAKE-AIDED STRATOCUMULUS THIS
AFTERNOON. NOTED THE HRRR KEYS SOME SHOWERS EARLY AFTERNOON AS THE
LAKE ERIE BREEZE CONVERGENCES WITH THE OTHERWISE WNW FLOW. THIS IS
PLAUSIBLE...BUT GIVEN THE ISOLATED NATURE OF THIS CONVERGENCE AREA
AND THE CAP SHOWN AT 10K FEET BY THE NAM...WILL ONLY CARRY SLIGHT
CHANCE POPS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
THROUGH 09Z...RADAR SHOWS A FAIRLY SOLID LINE OF SHOWERS WITH
EMBEDDED THUNDERSTORMS ACROSS AND JUST EAST OF LAKE ERIE. THIS
WILL BRING A PERIOD OF RAIN TO TAF SITES...AND PERHAPS A
THUNDERSTORM. CONDITIONS SHOULD MAINLY BE VFR OUTSIDE OF HEAVIER
RAIN SHOWERS WHICH MAY BRIEFLY LOWER VSBY TO AROUND 2SM.
FOLLOWING THE PASSAGE OF THE COLD FRONT EXPECT THE VFR LEVEL DECK TO
TEMPORARILY SCATTER OUT FRIDAY MORNING...ONLY TO FILL BACK IN AGAIN
WITH DAYTIME HEATING AS MOISTURE BECOMES TRAPPED BENEATH THE
SUBSIDENCE INVERSION. EXPECT MOST IF NOT ALL OF THIS POST-FRONTAL
CLOUD COVER TO BE VFR IN THE 035-050 KFT RANGE. THIS DECK SHOULD
SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES DIMINISH...AND
DRIER AIR MOVES IN.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY...VFR.
&&
.MARINE...
A COLD FRONT WILL MOVE ACROSS THE WATERS FROM WEST TO EAST THIS
MORNING. WINDS WILL BRIEFLY BE BREEZY AHEAD OF THE FRONT...BUT THE
SSW WIND DIRECTION IS UNFAVORABLE FOR BUILDING WAVES ON LAKE
ONTARIO. DO HAVE SOME CONCERN ON LAKE ERIE...WHERE A QUICK SHIFT TO
THE NW BEHIND THE THE FRONT EARLY THIS MORNING WILL LIKELY RESULT IN
A FEW HOURS OF CHOPPY CONDITIONS. BECAUSE OF THIS WILL ISSUE A BRIEF
SMALL CRAFT ADVISORY FOR LAKE ERIE THROUGH LATE MORNING.
WITH SHOWERS AND THUNDERSTORMS MOVING ACROSS THE LAKES THROUGH THIS
MORNING...AN ISOLATED WATERSPOUT CANNOT BE RULED OUT. THIS
SAID...TEMPERATURES ALOFT ARE NOT AS COLD AS A FEW DAYS AGO...SO ANY
ACTIVITY SHOULD NOT BE AS NEARLY WIDESPREAD.
THIS AFTERNOON...WINDS WILL SHIFT TO THE WNW BEHIND THE FRONT. THIS
FLOW WILL PERSIST...AND WILL LIKELY PRODUCE WAVES TO 5 FT ON EASTERN
PORTIONS OF LAKE ONTARIO MID-AFTERNOON ONWARD. WINDS WILL GRADUALLY
DIMINISH LATE TONIGHT.
FINE BOATING CONDITIONS ARE THEN EXPECTED FOR THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM
EDT SATURDAY FOR LOZ044-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
346 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE REGION THROUGH THIS MORNING
PRODUCING A BAND OF SHOWERS AND POSSIBLY A THUNDERSTORM. FOLLOWING
THE PASSAGE OF THE COLD FRONT EXPECT COOLER TEMPERATURES AND LESS
HUMID CONDITIONS FOR THIS AFTERNOON AND THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE MAIN FORECAST CHALLENGE FOR TODAY IS HOW WIDESPREAD RAINFALL
WILL BE WITH THE FRONTAL PASSAGE THIS MORNING. THROUGH 330
AM...RADAR SHOWS SHOWERS FILLING IN AHEAD OF THE FRONTAL
BOUNDARY...BUT STILL WEAK AND SOMEWHAT SCATTERED IN NATURE. MODEL
GUIDANCE IS CONSISTENT IN EXPANDING THIS AREA OF SHOWERS AS IT MOVES
ACROSS WESTERN NEW YORK...BUT MUCH OF THIS GUIDANCE HAS ALSO BEEN
OVERDONE IN THE DEVELOPMENT OF SHOWERS ACROSS LAKE ERIE THROUGH 06Z.
A SIGNIFICANT MCS TRACKED ACROSS KENTUCKY YESTERDAY EVENING...AND
THIS MAY HAVE TAKEN SOME OF THE MOISTURE WHICH WAS FORECAST TO
ENHANCE SHOWERS IN WESTERN NEW YORK. THIS SAID...A ROUND OF SHOWERS
STILL APPEAR LIKELY FOR WESTERN NEW YORK. A THUNDERSTORM IS STILL
POSSIBLE...THOUGH CONFIDENCE IN THIS IS LOW WITH NO STORMS UPSTREAM
YET.
THE 00Z GFS/AND 04Z HRRR HAD A FAIRLY GOOD HANDLE ON THE UPSTREAM
MCS...AND HAVE DONE BEST IN FORECASTING THE LIMITED SHOWER ON LAKE ERIE
DEVELOPMENT SO FAR. THESE STILL SUGGEST THAT SHOWERS WILL LIKELY
ACCOMPANY THE FRONT EARLY THIS...WITH STEADIEST RAIN SHOWERS BUFFALO
SOUTHWARD AS WINDS SHIFTING TO THE NORTHWEST SWEEP MOISTURE FROM
LAKE ERIE INTO WESTERN PORTIONS OF THE SOUTHERN TIER. THE FRONTAL
WILL BRING A COUPLE HOURS OF SHOWERS TO MOST...WITH QPFS MAINLY ON
THE LIGHT SIDE...LESS THAN A TENTH OF AN INCH. LOOK FOR A BIT MORE
THAN THIS BUFFALO SOUTHWARD...WHERE A BLEND OF THE GFS/HRRR FORECAST
AROUND A QUARTER INCH OF RAIN.
THE FRONT WILL EXIT TO THE EAST BY THIS AFTERNOON...WHICH WILL END
THE STEADY RAIN SHOWERS. HOWEVER...WITH COOLER AIR MOVING IN BEHIND
THE FRONT...AND THE RELATIVELY WARM LAKES...EXPECT ANY BRIEF
CLEARING WILL LIKELY FILL IN WITH LAKE-AIDED STRATOCUMULUS THIS
AFTERNOON. NOTED THE HRRR KEYS SOME SHOWERS EARLY AFTERNOON AS THE
LAKE ERIE BREEZE CONVERGENCES WITH THE OTHERWISE WNW FLOW. THIS IS
PLAUSIBLE...BUT GIVEN THE ISOLATED NATURE OF THIS CONVERGENCE AREA
AND THE CAP SHOWN AT 10K FEET BY THE NAM...WILL ONLY CARRY SLIGHT
CHANCE POPS.
OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION FROM THE WEST
TONIGHT. THIS SHOULD RESULT IN A GENERAL DRYING TREND...WHERE
LINGERING CLOUDS FROM THE DAY SHOULD DISSIPATE. THIS SAID...A MORE
WESTERLY FLOW ON LAKE ONTARIO MAY ALLOW FOR LAKE CONVERGENCE CLOUDS
TO DEVELOP AND MOVE EAST OF LAKE ONTARIO LATE TONIGHT. THERE SHOULD
BE AMPLE PERIODS OF CLEARING TO ALLOW FOR TEMPERATURES TO COOL
CONSIDERABLY TONIGHT. LOWS WILL LIKELY RANGE FROM THE MID AND UPPER
40S IN THE COOL VALLEYS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...TO
THE LOWER 50S ELSEWHERE.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DURING THE WEEKEND...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
DEEP UPPER TROUGHING CENTERED NEAR JAMES BAY...WHILE SURFACE BASED
RIDGING OVER THE OHIO VALLEY AND LOWER LAKES GRADUALLY EXPANDS
NORTHEASTWARD INTO NEW ENGLAND.
UNDER THIS PATTERN...COOLER AND MAINLY DRY WEATHER WILL BE
PREDOMINANT. WHILE TEMPS ALOFT WILL BE CERTAINLY COOL ENOUGH FOR A
LAKE RESPONSE...THE RELATIVELY DRY NATURE OF OUR AIRMASS AND A FAIR
AMOUNT OF LOW LEVEL SHEAR SHOULD PREVENT MUCH MORE THAN SOME
LAKE-DRIVEN STRATOCU DOWNWIND OF THE LAKES EARLY SATURDAY
MORNING...AND AGAIN LATER SATURDAY NIGHT INTO EARLY SUNDAY.
SYNOPTICALLY...THE NAM/GFS/ECMWF ALL TRY TO SPIT OUT SOME SPOTTY
LIGHT SHOWERS ACROSS PARTS OF THE AREA SUNDAY AFTERNOON WITH DAYTIME
HEATING AND THE APPROACH OF A MODEST SHORTWAVE...BUT THIS STILL
APPEARS TO BE WORTHY OF NO MORE THAN SOME SLIGHT CHANCE POPS GIVEN
ONLY VERY LIMITED AMOUNTS OF AVAILABLE MOISTURE.
IN TERMS OF ACTUAL TEMPERATURES...850 MB READINGS WILL AVERAGE IN
THE +7C TO +9C RANGE SATURDAY...AND A DEGREE OR SO WARMER THAN THAT
ON SUNDAY. THIS WILL TRANSLATE INTO COMFORTABLE HIGHS IN THE LOWER
70S ON SATURDAY...AND THE LOWER TO MID 70S ON SUNDAY. MEANWHILE...
NIGHTTIME LOWS SATURDAY NIGHT WILL RANGE FROM THE MID 40S ACROSS
INTERIOR SECTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE
LOWER 50S ALONG THE LAKE PLAINS...BEFORE MODERATING A FEW DEGREES
FOR SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE COOL WEATHER OF THE SHORT TERM PERIOD WILL PERSIST INTO THE
FIRST COUPLE DAYS OF THE EXTENDED RANGE AS WELL...AS THE LARGE-SCALE
UPPER TROUGH REMAINS IN PLACE ACROSS THE GREAT LAKES AND NORTHEAST.
WITH DAYTIME HEATING OF THE STILL-COOL AIRMASS ALOFT...THE PASSAGE
OF A VERY WEAK SURFACE TROUGH COULD SET OFF SOME ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY ON MONDAY...WITH THE APPROACH AND PASSAGE OF
THE MAIN UPPER TROUGH AXIS POSSIBLY DOING THE SAME ON TUESDAY. WILL
ACCORDINGLY KEEP SLIGHT CHANCE POPS IN PLACE FOR BOTH DAYS...WITH
ANY PRECIP THAT DOES FORM DIMINISHING WITH THE LOSS OF HEATING BOTH
MONDAY AND TUESDAY EVENINGS. 850 MB TEMPS LINGERING IN THE +8C TO
+10C RANGE WILL SUPPORT HIGHS IN THE LOWER TO MID 70S BOTH
DAYS...WITH NIGHTTIME LOWS IN THE 50S EXPECTED BOTH NIGHTS.
AFTER THAT...THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON THE CORE
OF THE UPPER TROUGH LIFTING OFF INTO LABRADOR AND THEN INTO THE
NORTHERN ATLANTIC...WITH A RELATIVELY FLAT ZONAL FLOW SETTING UP
ACROSS THE LOWER LAKES AND NORTHEAST IN ITS WAKE. THE ENSUING WARM
AIR ADVECTION PATTERN WILL RESULT IN A GRADUAL WARMING TREND THROUGH
THE PERIOD...WITH DAYTIME HIGHS RECOVERING TO NEAR THE 80 DEGREE
MARK BY THURSDAY...AND NIGHTTIME LOWS ALSO MODERATING A FEW DEGREES
EACH NIGHT. AS FOR PRECIP CHANCES...THESE LOOK TO BE PRACTICALLY NIL
ON WEDNESDAY WITH THE DEPARTURE OF THE TROUGH AND LOW-LEVEL RIDGING
REMAINING IN PLACE...BEFORE CLIMBING BACK INTO THE SLIGHT CHANCE
RANGE ON THURSDAY WITH THE APPROACH OF ANOTHER WEAK SURFACE TROUGH.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
THROUGH 06Z...RADAR SHOWS BROKEN AND GENERALLY LIGHT SHOWERS
UPSTREAM WITH THE FRONT. EXPECT LAKE ERIE TO PROVIDE SOME MOISTURE
ENHANCEMENT...BUT EVEN WITH THIS THERE SHOULD ONLY BE A BRIEF
PERIOD OF RAIN SHOWERS NEAR THE FRONTAL PASSAGE. AHEAD OF THE
FRONT...EXPECT CIGS/VSBY TO REMAIN IN THE VFR CATEGORY...EVEN AS
SHOWERS MOVE IN. WITH THE FRONT...SURFACE WINDS WILL SHIFT TO THE
NW...AND THIS MAY BRING A BRIEF PERIOD WHERE CIGS LOWER WHILE RAIN
SHOWERS LINGER. TSTMS CANNOT COMPLETELY BE RULED OUT...BUT ANY
SHOULD BE ISOLATED IN NATURE.
BASED ON VAD WIND PROFILE AND RAP FORECASTS....THERE WILL BE A
BRIEF PERIOD OF 30 TO 40 KT WINDS DOWN TO AROUND 1500 FEET THROUGH
DAYBREAK. WHILE MARGINAL...WILL CARRY A FEW HOURS OF LLWS SINCE
THIS IS NOT EXPECTED TO MIX DOWN TO THE SURFACE READILY.
FOLLOWING THE PASSAGE OF THE COLD FRONT EXPECT THE VFR LEVEL DECK TO
TEMPORARILY SCATTER OUT FRIDAY MORNING...ONLY TO FILL BACK IN AGAIN
WITH DAYTIME HEATING AS MOISTURE BECOMES TRAPPED BENEATH THE
SUBSIDENCE INVERSION. EXPECT MOST IF NOT ALL OF THIS POST-FRONTAL
CLOUD COVER TO BE VFR IN THE 035-050 KFT RANGE. THIS DECK SHOULD
SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES DIMINISH...AND
DRIER AIR MOVES IN.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY...VFR.
&&
.MARINE...
A COLD FRONT WILL MOVE ACROSS THE WATERS FROM WEST TO EAST THIS
MORNING. WINDS WILL BRIEFLY BE BREEZY AHEAD OF THE FRONT...BUT THE
SSW WIND DIRECTION IS UNFAVORABLE FOR BUILDING WAVES ON LAKE
ONTARIO. DO HAVE SOME CONCERN ON LAKE ERIE...WHERE A QUICK SHIFT TO
THE NW BEHIND THE THE FRONT EARLY THIS MORNING WILL LIKELY RESULT IN
A FEW HOURS OF CHOPPY CONDITIONS. BECAUSE OF THIS WILL ISSUE A BRIEF
SMALL CRAFT ADVISORY FOR LAKE ERIE THROUGH LATE MORNING.
WITH SHOWERS AND THUNDERSTORMS MOVING ACROSS THE LAKES THROUGH THIS
MORNING...AN ISOLATED WATERSPOUT CANNOT BE RULED OUT. THIS
SAID...TEMPERATURES ALOFT ARE NOT AS COLD AS A FEW DAYS AGO...SO ANY
ACTIVITY SHOULD NOT BE AS NEARLY WIDESPREAD.
THIS AFTERNOON...WINDS WILL SHIFT TO THE WNW BEHIND THE FRONT. THIS
FLOW WILL PERSIST...AND WILL LIKELY PRODUCE WAVES TO 5 FT ON EASTERN
PORTIONS OF LAKE ONTARIO MID-AFTERNOON ONWARD. WINDS WILL GRADUALLY
DIMINISH LATE TONIGHT.
FINE BOATING CONDITIONS ARE THEN EXPECTED FOR THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM
EDT SATURDAY FOR LOZ044-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
133 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE AREA LATE TONIGHT PRODUCING A
BAND OF SHOWERS AND THUNDERSTORMS. FOLLOWING THE PASSAGE OF THE COLD
FRONT EXPECT COOLER TEMPERATURES AND LESS HUMID CONDITIONS FOR
FRIDAY AFTERNOON THROUGH THIS UPCOMING WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
THICKER MID/HIGH CLOUDS JUST UPSTREAM WILL OVERSPREAD THE REGION
OVERNIGHT FROM WEST TO EAST. A BROKEN LINE OF SHOWERS UPSTREAM
ACROSS EASTERN LOWER MICHIGAN AND LAKE HURON CONTINUE TO REALLY
STRUGGLE TO GAIN INTENSITY AND COVERAGE. A MASSIVE MCS WHICH FORMED
EARLIER UPSTREAM ACROSS THE OHIO VALLEY IS LIKELY ROBBING MUCH OF
THE DEEPER MOISTURE WHICH WAS DESTINED FOR FARTHER NORTH ALONG THE
FRONT...AND THIS MAY CONTINUE TO HURT THE CONVECTIVE POTENTIAL ALONG
THE PORTION OF THE COLD FRONT WHICH WILL REACH WESTERN NY LATE
TONIGHT. FOR NOW HAVE HELD ONTO HIGH LIKELY POPS AND IT WILL
PROBABLY RAIN IN MOST AREAS...BUT AMOUNTS ARE LOOKING LESS AND LESS
AND THE THUNDER POTENTIAL IS LOOKING LOWER.
LATEST 18Z AND 00Z MESOSCALE MODEL GUIDANCE AND THE HIGH RESOLUTION
HRRR MODEL RUNS HAVE SLOWED THE APPROACH OF THIS CONVECTIVE LINE A
FEW HOURS FROM PREVIOUS RUNS...AND EXTRAPOLATION OF THE CURRENT LINE
POSITION SUGGESTS CONVECTION WILL ARRIVE IN FAR WESTERN NY AROUND
08Z-09Z...THEN SPREAD TO THE EASTERN LAKE ONTARIO REGION BY 12Z.
HAVE ADJUSTED TIMING IN THE GRIDDED FORECASTS AND ZFP BY AN HOUR OR
TWO TO ACCOUNT FOR THESE LATEST TIMING THOUGHTS. SHOULD BE DRY IN
WESTERN NY UNTIL ABOUT 3AM...AND THE ENTIRE NIGHT EAST OF THE
GENESEE RIVER.
WITH AN INCREASING SSW BREEZE OVERNIGHT IT WILL STAY MILD...WITH
LOWS ONLY IN THE UPPER 60S ON THE LAKE PLAINS AND LOWER 60S WELL
INLAND.
ON FRIDAY...THE FRONT SHOULD MOVE QUICKLY THROUGH THE REGION WITH
SHOWERS AND THUNDERSTORMS ENDING FROM WEST TO EAST DURING THE
MORNING.
OTHERWISE...STRATO-CU CLOUDS WILL QUICKLY SPREAD OUT UNDER AN
INVERSION AND MOIST LOW LEVEL AIRMASS. ANY MORNING CLEARING JUST
BEHIND THE COLD FRONT SHOULD THEREFORE BE REPLACED BY AT LEAST
MOSTLY CLOUDY CONDITIONS FOR THE MAJORITY OF WESTERN NY UNDER AN
UPSLOPE NW FLOW.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
DRY AND COOL WEATHER IS EXPECTED THROUGH THIS WEEKEND WITH
TEMPERATURES BELOW NORMAL. ON FRIDAY EVENING A DEEP SURFACE
LOW...NEAR 990MB...WILL BE LOCATED OVER SOUTHERN HUDSON BAY WITH
COLD FRONT EXTENDING SOUTHEAST TO NEW ENGLAND THEN SOUTHWEST ACROSS
DOWNSTATE NY AND THEN SOUTHERN PA. BY THEN ALL OF THE FORECAST AREA
SHOULD BE CLEAR OF SHOWER AND THUNDERSTORM ACTIVITY WITH THE FRONT
TO THE EAST. A SURFACE HIGH WILL BE CENTERED OVER IOWA AND RIDGING
EAST ACROSS WESTERN NY. COLD AIR ADVECTION WILL BE IN PLACE OUT OF
THE NORTHWEST WITH CLEAR SKIES AND DRYING MOISTURE PROFILES.
THE 12Z GFS INDICATES THE DEEP UPPER LOW COUPLED ABOVE THE SURFACE
LOW OVER SOUTHERN HUDSON BAY WILL FURTHER DEEPEN THROUGH SATURDAY
WITH A BROAD TROUGH SETTLING OVER THE EASTERN TWO-THIRDS OF THE
COUNTRY. WITHIN THIS COOL AND DRY AIRMASS...PRECIPITABLE WATERS
FALLING TO AROUND A HALF INCH...NO PRECIPITATION IS EXPECTED FOR THE
AREA. LIMITED PERIODS OF CLOUDINESS WILL OCCUR WITH PASSAGE OF ANY
WEAK SHORTWAVES MOVING THOUGH THE TROUGH AND...ON A MESOSCALE
LEVEL...DOWNWIND OF THE LAKES. 850MB TEMPS WILL FALL TO BETWEEN +5C
AND +9C SATURDAY AND SUNDAY. THESE COOL TEMPS ALOFT COMBINED WITH
LAKE TEMPS AROUND +24 WILL PRODUCE LAKE EFFECT STRATOCU BUT MOISTURE
TOO LIMITED FOR PRECIP.
FOR TEMPERATURES...NORMAL HIGHS RUN IN THE UPPER 70S AND LOWS IN THE
LOW 60S FOR MID AUGUST. THE COOL AIRMASS SETTLING OVER THE STATE
WILL KEEP HIGHS AND LOWS SATURDAY AND SUNDAY 5 TO 10 DEGREES BELOW
NORMAL. HIGHS RUNNING IN THE LOWER 70S MOST LOCATIONS WITH UPPER 60S
IN THE SOUTHERN TIER AND TUG HILL. LOWS WILL BE SIMILARLY BELOW
NORMAL FALLING INTO THE UPPER 40S TO LOW 50S EACH NIGHT AWAY FROM
THE LAKES WITH MID TO UPPER 50S NEAR THE LAKE SHORES.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
MONDAY WILL START WITH THE REGION STILL UNDER THE SEASONABLY COOL
WEATHER PATTERN FROM THE WEEKEND. THE 12Z MODELS THEN SHOW BY
TUESDAY AN APPROACHING UPPER LEVEL DISTURBANCE AND EXPANSION OF THE
WEST COAST RIDGE TO THE EAST. THIS WILL FINALLY HELP TO LIFT THE
EASTERN TROUGH BACK INTO CANADA AND RESULT IN A WARMER/MOISTENING
SOUTHWEST FLOW DEVELOPING ACROSS THE STATE UNDER A MORE ZONAL/WAVY
FLOW OVER THE GREAT LAKES.
A POSSIBLE WEAK SURFACE TROUGH/FRONT LOOK POSSIBLE TO CROSS THE
REGION SOMETIME MONDAY NIGHT INTO TUESDAY NIGHT SET OFF BY THE UPPER
DISTURBANCE. INCLUDED A SLIGHT CHANCE FOR SHOWERS EARLY IN THE WEEK
TO COVER FOR THIS AND ANOTHER SLIGHT CHANCE ON THURSDAY WITH ANOTHER
FRONT WORKING TOWARD THE AREA. BEHIND THE EARLY WEEK SYSTEM WE WILL
TRANSITION FROM COOLER WEATHER BACK TO MORE SEASONABLE TEMPERATURES
BY THURSDAY. DAILY HIGHS WILL CLIMB BACK TO NEAR OR SLIGHTLY ABOVE
NORMAL...UPPER 70S/LOW 80S...BY THE END OF NEXT WEEK. LOWS WILL ALSO
NUDGE UP HIGHER WITH DEWPOINTS RUNNING IN THE MID TO UPPER 50S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
THROUGH 06Z...RADAR SHOWS BROKEN AND GENERALLY LIGHT SHOWERS
UPSTREAM WITH THE FRONT. EXPECT LAKE ERIE TO PROVIDE SOME MOISTURE
ENHANCEMENT...BUT EVEN WITH THIS THERE SHOULD ONLY BE A BRIEF
PERIOD OF RAIN SHOWERS NEAR THE FRONTAL PASSAGE. AHEAD OF THE
FRONT...EXPECT CIGS/VSBY TO REMAIN IN THE VFR CATEGORY...EVEN AS
SHOWERS MOVE IN. WITH THE FRONT...SURFACE WINDS WILL SHIFT TO THE
NW...AND THIS MAY BRING A BRIEF PERIOD WHERE CIGS LOWER WHILE RAIN
SHOWERS LINGER. TSTMS CANNOT COMPLETELY BE RULED OUT...BUT ANY
SHOULD BE ISOLATED IN NATURE.
BASED ON VAD WIND PROFILE AND RAP FORECASTS....THERE WILL BE A
BRIEF PERIOD OF 30 TO 40 KT WINDS DOWN TO AROUND 1500 FEET THROUGH
DAYBREAK. WHILE MARGINAL...WILL CARRY A FEW HOURS OF LLWS SINCE
THIS IS NOT EXPECTED TO MIX DOWN TO THE SURFACE READILY.
FOLLOWING THE PASSAGE OF THE COLD FRONT EXPECT THE VFR LEVEL DECK TO
TEMPORARILY SCATTER OUT FRIDAY MORNING...ONLY TO FILL BACK IN AGAIN
WITH DAYTIME HEATING AS MOISTURE BECOMES TRAPPED BENEATH THE
SUBSIDENCE INVERSION. EXPECT MOST IF NOT ALL OF THIS POST-FRONTAL
CLOUD COVER TO BE VFR IN THE 035-050 KFT RANGE. THIS DECK SHOULD
SLOWLY SCATTER OUT TONIGHT AS WINDS OFF THE LAKES DIMINISH...AND
DRIER AIR MOVES IN.
OUTLOOK...
SATURDAY...POSSIBLE MVFR/IFR IN FOG EARLY OTHERWISE VFR.
SUNDAY...VFR.
MONDAY...CHANCE OF SHOWERS/TSTMS. MAINLY VFR.
TUESDAY...VFR.
&&
.MARINE...
A COLD FRONT WILL CROSS THE LOWER LAKES TONIGHT ALONG WITH THE
LIKELIHOOD OF A ROUND OF SHOWERS AND THUNDERSTORMS...SOME OF
WHICH COULD PRODUCE LOCALLY GUSTY WINDS. BEHIND THE FRONT...A BRISK
WESTERLY FLOW OF COOLER AIR WILL SET UP ACROSS LAKE ONTARIO ON
FRIDAY...WITH WINDS AND WAVES POTENTIALLY REACHING ADVISORY CRITERIA.
FINE BOATING CONDITIONS ARE THEN EXPECTED FOR THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ZAFF
NEAR TERM...HITCHCOCK/ZAFF
SHORT TERM...SMITH
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...ZAFF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
130 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT...WILL APPROACH THE AREA THIS EVENING AND MOVE INTO
CENTRAL NORTH CAROLINA ON SATURDAY.. MEANWHILE...AN UPPER LEVEL
TROUGH WILL DEVELOP OVER THE EASTERN US AND BRING PERIODS OF SHOWERS
AND STORMS THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 955 AM FRIDAY...
TODAY...
CLEAR SKIES ARE OBSERVED ACROSS THE AREA THIS MORNING AS
CONVECTIVE/FRONTAL CLOUD COVER REMAINS MOSTLY WEST OF THE
MOUNTAINS. THE 12Z KGSO RAOB HAD A 1408M LOW LEVEL
THICKNESS...WHICH YIELDS HIGHS OF 88-92 UNDER FULL SUN...CONSISTENT
WITH THE CURRENT FORECAST. REMNANT OUTFLOW AND A SHEARING LOBE OF
VORTICITY APPROACHING THE MOUNTAINS FROM THE WEST WILL BE THE MAIN
FOCUS FOR ANY CONVECTION THIS AFTERNOON. THE RAP SHOWS TWO AREAS OF
STRONGER VORTICITY...ONE DIVING SOUTH INTO NORTHERN GA..AND THE
SECOND STRADDLING THE NC/VA BORDER THIS EVENING. DEWPOINTS ARE
CURRENTLY IN THE LOW TO MID 60S OVER THE WESTERN PIEDMONT..AND
ALTHOUGH THE LEE TROUGH WILL SHARPEN AHEAD OF THE BROAD CYCLONIC
FLOW DEVELOPING OVER THE EASTERN US...GUIDANCE DOES NOT SHOW MUCH
DEWPOINT RECOVERY ALONG THE TROUGH AXIS UNTIL LATE THIS EVENING AND
OVERNIGHT. COMBINED WITH WEAK LAPSE RATES ALOFT...ONLY A WEAK
INSTABILITY AXIS OF 500 TO MAYBE 1000 J/KG MLCAPE IS ANTICIPATED
EAST OF THE MOUNTAINS THIS AFTERNOON. PW IS RELATIVELY LOW ACROSS
THE CWA THIS MORNING...DOWN AROUND ONE INCH...BUT IS FORECAST TO
SURGE TO NEAR 1.75 INCHES THIS EVENING AS GOOD MID-LEVEL MOISTURE
ADVECTS IN FROM THE WEST. SCATTERED SHOWERS AND STORMS MAY HAVE
INITIALLY HAVE A HARD TIME MOVING EAST OF THE MOUNTAINS THIS
AFTERNOON...BUT STEEP LOW LEVEL LAPSE RATES AND 20-25KT OF MID LEVEL
FLOW COULD SUPPORT ENHANCED DOWNDRAFTS FROM EVAPORATIONAL COOLING
AND A FEW STORM CLUSTERS WITH ORGANIZED COLD POOLS IF CONVECTION IS
AS ROBUST AS A COUPLE OF THE CAMS ARE SHOWING. -SMITH
OVERNIGHT: SHOWERS AND STORMS WILL DRIFT EASTWARD IN A WEAKENING
STATE OWING TO NOCTURNAL COOLING/STABILIZATION OVERNIGHT. WHILE
CONTINUED 20-30 KTS OF EFFECTIVE BULK SHEAR WILL PERSIST...THIS WILL
LIKELY BE INSUFFICIENT TO COMPENSATE FOR THE RELATIVE LACK OF
STEADILY DECREASING BUOYANCY...SO ANY PRIOR SEVERE WEATHER THREAT
SHOULD DIMINISH PRIOR TO MIDNIGHT. NONETHELESS...SOME SHOWERS AND
ISOLATED STORMS ARE APT TO CONTINUE THROUGHOUT THE NIGHT...AS THE
SYNOPTIC SURFACE FRONTAL -- WHICH SIGNIFICANTLY LAGS THE ONGOING
PRE-FRONTAL MCS/S...AND ASSOCIATED OUTFLOW THAT WILL LIKELY HAVE A
DIFFICULT TIME CRESTING THE BLUE RIDGE TODAY -- GRADUALLY SETTLES
INTO AT LEAST THE NORTHWEST PIEDMONT TOWARD SUNRISE. CLOUDY OR
MOSTLY SO...WITH LOWS IN LOWER 70S FOR MOST.
SATURDAY: THERE ARE MIXED SIGNALS WITH RESPECT TO CONVECTIVE
COVERAGE AND INTENSITY ON SATURDAY. ON ONE HAND...LOW LEVEL FORCING
SHOULD BE QUITE STRONG AS THE LOW LEVEL FRONTAL ZONE...DEEP THROUGH
AT LEAST H85...SETTLES SOUTHEASTWARD THROUGH ALL OF CENTRAL NC BY
EVENING - A CHANGE FROM THE EARLIER EXPECTATION THAT THE BOUNDARY
WOULD STALL OVERHEAD THROUGH EARLY NEXT WEEK. ON THE OTHER
HAND...HOWEVER...THE PRECEDING PASSAGE OF THE LEAD MID LEVEL TROUGH
AXIS THROUGH CENTRAL NC FRI NIGHT...AND ASSOCIATED TRAILING NEUTRAL
TO WEAKLY RISING HEIGHTS ALOFT...SUGGESTS DEEPER LAYER SUBSIDENCE
WILL BE IN PLACE OVERHEAD. GIVEN THE DEPTH AND VIGOR OF THE LOW
LEVEL FRONTAL ZONE...IN CONJUNCTION WITH LOW LCL/LFC HEIGHTS AMIDST
HIGH BL MOISTURE CHARACTERIZED BY WARM SECTOR SURFACE DEWPOINTS AOA
70 DEGREES AND TEMPERATURES IN THE 80S...WILL LEAN TOWARD A HIGHER
LIKELIHOOD OF SHOWERS AND STORMS...DESPITE THE DEEPER LAYER
SUBSIDENCE. WHILE PRECIPITATION CHANCES SHOULD DIMINISH FROM
NORTHWEST TO SOUTHEAST WITH TIME AND THE PASSAGE OF THE FRONTAL
ZONE...A FEW ANAFRONTAL SHOWERS MAY CONTINUE TO PERCOLATE ON THE
IMMEDIATE COOL SIDE OF THE BOUNDARY WHERE ISENTROPIC UPGLIDE AND
LINGERING...ALBEIT DIMINISHED WEAK INSTABILITY...WILL COINCIDE.
WHILE EFFECTIVE BULK SHEAR VALUES WILL INCREASE INTO THE 25 TO 40 KT
RANGE BY LATE AFTERNOON AND EVENING...IN ADVANCE OF A S/W TROUGH
FORECAST TO LIFT THROUGH THE MIDDLE ATLANTIC STATES...THIS BELT OF
STRONGER FLOW IS FORECAST TO LAG THE MODERATELY UNSTABLE WARM
SECTOR. AS SUCH...MULTI-CELL CONVECTIVE MODES WITH A PRIMARY THREAT
OF DAMAGING WINDS SHOULD DOMINATE...ALTHOUGH THERE MAY BE A RELATIVE
SWEET SPOT IN A NARROW CORRIDOR ROUGHLY FROM ROCKINGHAM TO RALEIGH
TO ROANOKE RAPIDS...WHERE MORE OPTIMAL VALUES OF SHEAR AND
INSTABILITY MAY CO-EXIST AND SUPPORT A CONDITIONAL THREAT OF BRIEF
SUPERCELLULAR STRUCTURES.
SAT NIGHT: DRY WITH POST-FRONTAL NORTH TO NORTHEASTERLY FLOW...WITH
LOWS IN THE 64 TO 70 DEGREE RANGE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 320 AM EDT...
SURFACE TROUGH FORECAST TO BE EAST AND SOUTHEAST OF CENTRAL NORTH
CAROLINA AT SUNRISE SUNDAY... BUT WITH SURFACE DEWPOINTS IN EXCESS
OF 65 DEGREES AND A BROAD UPPER TROUGH EXTENDING SOUTH INTO THE GULF
STATES... RAIN CHANCES WILL CONTINUE. PRECIPITABLE WATERS ROUGHLY
1.5 INCHES NORTHWEST TO 1.75 INCHES SOUTHWEST... WITH SURFACE BASED
CAPE IN EXCESS OF 2500 JOULES SOUTHEAST... TO NEAR 2000 NORTHWEST.
MID LEVEL WINDS OF 35 TO 45 KNOTS AND MIXING HEIGHTS ONLY TO 4000
FEET. THE AIR MASS IS PRIMED FOR A FEW SEVERE THUNDERSTORMS IN THE
AFTERNOON WITH DAMAGING WINDS THE MAIN THREAT. THE BIGGEST CONCERN
IS LACK OF A SIGNIFICANT TRIGGER OTHER THAN DAYTIME HEATING. HOWEVER
CONVECTIVE TRIGGER TEMPERATURES ARE A LOW 80 TO 85 DEGREES... AND
WILL RETAIN AFTERNOON POPS OF 50 TO 60 PERCENT.
LOSS OF HEATING SHOULD END MOST CONVECTION... BUT A THUNDERSTORM OR
TWO COULD PERSIST PAST MIDNIGHT IN THIS ENVIRONMENT.
THE UPPER TROUGH CONTINUES ITS SLOW APPROACH FROM THE WEST MONDAY.
THE MID LEVEL PRESSURE GRADIENT TIGHTENS WITH A DEEP LAYER OF
SOUTHWEST WINDS OF 30 TO 45 KNOTS... STRONGEST SOUTHEAST.
PRECIPITABLE WATERS PERHAPS EXCEEDING TWO INCHES SOUTHEAST. 850
MILLIBAR TROUGH WILL BE NEAR OR EAST OF HIGHWAY ONE... AND HIGHEST
RAIN CHANCES WILL BE IN THAT AREA MONDAY AFTERNOON. FORTY PERCENT
POPS NORTHWEST TO 50 SOUTHEAST WITH THE THREAT FOR DAMAGING WINDS
SIMILARLY HIGHER SOUTHEAST THAN NORTHWEST DUE TO HIGHER INSTABILITY
AND POTENTIAL ENERGY.
WINDS ALOFT BEGIN TO WEAKEN A BIT MONDAY NIGHT... WITH SOME DRYING
ALOFT IN THE WEST AFTER MIDNIGHT. UNLESS THERE IS SOME MINOR SHORT
WAVE FOR UPPER LEVEL SUPPORT... MOST CONVECTION SHOULD END IN THE
EVENING. A VERY FEW SHOWERS OR A THUNDERSTORM COULD PERSIST PAST
MIDNIGHT... MAINLY NEAR AND EAST OF HIGHWAY ONE.
AFTERNOON LOW LEVEL THICKNESSES ABOUT FIVE METERS BELOW CLIMATOLOGY
SUNDAY... AND TEN TO FIFTEEN METERS MONDAY. TEMPERATURES BELOW
NORMAL... WITH HIGH TEMPERATURES 80 TO 85 SUNDAY... LOW 80S MONDAY.
LOWS BELOW NORMAL IN SPITE OF CLOUDS... AT LOWER 60S NORTHWEST TO
MID 60S SOUTHEAST.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 340 PM FRIDAY...
ROUGH CONSENSUS IN BEGINNING TO SHEAR OUT THE UPPER TROUGH TO OUR
WEST TUESDAY AS IT LIFTS NORTHEAST... WITH THE ECMWF MORE AGGRESSIVE
THAN THE GFS IN THIS PROCESS. A WEAK SURFACE TROUGH FORECAST NEAR OR
EAST OF INTERSTATE 95... AND WILL PLACE HIGHEST RAIN CHANCES THERE.
30 PERCENT RAIN CHANCE WELL EAST... WHICH MAY PROVE TOO LOW. LESS
THAN ONE IN SEVEN ELSEWHERE.
SIGNIFICANT DIFFERENCES IN THE UPPER LEVEL PATTERN FOR WEDNESDAY AND
THURSDAY IN THE MODELS... AND FORECAST IS OF BELOW AVERAGE
CONFIDENCE. ROUGH AGREEMENT IN SOUTHWEST FLOW ALOFT. THE CURRENT
FORECAST OF SLIGHT AFTERNOON RAIN CHANCES IS A BIT BELOW CLIMATOLOGY
BUT WITHIN REASON GIVEN UNCERTAINTY.
AFTERNOON TEMPERATURES WILL BE FORECAST NEAR TO A TOUCH BELOW
CLIMATOLOGY AT LOW TO MID 80S. LOW TEMPERATURES LOWER 60S NORTHWEST
TO MID 60S ELSEWHERE.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 130 PM FRIDAY...
VFR CONDITIONS WILL CONTINUE FOR MOST OF THE AFTERNOON AND EVEN
ACROSS MUCH OF THE AREA. A FEW SHOWERS AND STORMS WILL PROGRESS
FROM THE MOUNTAINS TOWARDS THE WESTERN PIEDMONT...BUT IT IS STILL
UNCERTAIN AS TO HOW FAR EAST THEY WILL INITIALLY MAKE IT AND/OR HOW
STRONG THEY WILL BE. KINT/KGSO SHOULD SEE SOME SHOWERS AND POSSIBLY
ISOLATED STORMS IN THE VICINITY OF THE TERMINALS BY 21-22Z. SHOWERS
AND STORMS WILL THEN CONTINUE EAST ACROSS CENTRAL NC THIS EVENING
AND TONIGHT ALONG A SURFACE TROUGH AND AHEAD OF A COLD FRONT
APPROACHING FROM THE WEST. IT IS POSSIBLE THAT THE COVERAGE OF
SHOWERS MAY INCREASE OVER THE CENTRAL PIEDMONT PRIOR TO
MIDNIGHT...BUT ANY ISOLATES STORMS RE NOT EXPECTED TO BE STRONG AT
THAT POINT. THUS..OUTSIDE OF THE HEAVIEST SHOWERS...VFR CONDITIONS
SHOULD PREVAIL.
THE SHOWERS WILL DIE OFF BY SUNRISE SATURDAY MORNING...BUT SHOULD
REDEVELOP BY MIDDAY SATURDAY AS THE COLD FRONT MOVES INTO THE
AREA...AND STRONG STORMS ARE POSSIBLE FROM KRDU EASTWARD DURING THE
AFTERNOON.
OUTLOOK...
WITH A LARGE UPPER TROUGH EXPECTED TO REMAIN OVER THE
EASTERN US THROUGH EARLY NEXT WEEK...PERIODS OF SHOWERS AND STORMS
WILL BE POSSIBLE EACH DAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS/SMITH
SHORT TERM...
LONG TERM...
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
955 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A LEE TROUGH WILL REMAIN OVER THE PIEDMONT TODAY...IN ADVANCE OF A
COLD FRONT THAT WILL APPROACH SLOWLY FROM THE NORTHWEST AND SETTLE
THROUGH THE AREA ON SATURDAY.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 955 AM FRIDAY...
TODAY...
CLEAR SKIES ARE OBSERVED ACROSS THE AREA THIS MORNING AS
CONVECTIVE/FRONTAL CLOUD COVER REMAINS MOSTLY WEST OF THE
MOUNTAINS. THE 12Z KGSO RAOB HAD A 1408M LOW LEVEL
THICKNESS...WHICH YIELDS HIGHS OF 88-92 UNDER FULL SUN...CONSISTENT
WITH THE CURRENT FORECAST. REMNANT OUTFLOW AND A SHEARING LOBE OF
VORTICITY APPROACHING THE MOUNTAINS FROM THE WEST WILL BE THE MAIN
FOCUS FOR ANY CONVECTION THIS AFTERNOON. THE RAP SHOWS TWO AREAS OF
STRONGER VORTICITY...ONE DIVING SOUTH INTO NORTHERN GA..AND THE
SECOND STRADDLING THE NC/VA BORDER THIS EVENING. DEWPOINTS ARE
CURRENTLY IN THE LOW TO MID 60S OVER THE WESTERN PIEDMONT..AND
ALTHOUGH THE LEE TROUGH WILL SHARPEN AHEAD OF THE BROAD CYCLONIC
FLOW DEVELOPING OVER THE EASTERN US...GUIDANCE DOES NOT SHOW MUCH
DEWPOINT RECOVERY ALONG THE TROUGH AXIS UNTIL LATE THIS EVENING AND
OVERNIGHT. COMBINED WITH WEAK LAPSE RATES ALOFT...ONLY A WEAK
INSTABILITY AXIS OF 500 TO MAYBE 1000 J/KG MLCAPE IS ANTICIPATED
EAST OF THE MOUNTAINS THIS AFTERNOON. PW IS RELATIVELY LOW ACROSS
THE CWA THIS MORNING...DOWN AROUND ONE INCH...BUT IS FORECAST TO
SURGE TO NEAR 1.75 INCHES THIS EVENING AS GOOD MID-LEVEL MOISTURE
ADVECTS IN FROM THE WEST. SCATTERED SHOWERS AND STORMS MAY HAVE
INITIALLY HAVE A HARD TIME MOVING EAST OF THE MOUNTAINS THIS
AFTERNOON...BUT STEEP LOW LEVEL LAPSE RATES AND 20-25KT OF MID LEVEL
FLOW COULD SUPPORT ENHANCED DOWNDRAFTS FROM EVAPORATIONAL COOLING
AND A FEW STORM CLUSTERS WITH ORGANIZED COLD POOLS IF CONVECTION IS
AS ROBUST AS A COUPLE OF THE CAMS ARE SHOWING. -SMITH
OVERNIGHT: SHOWERS AND STORMS WILL DRIFT EASTWARD IN A WEAKENING
STATE OWING TO NOCTURNAL COOLING/STABILIZATION OVERNIGHT. WHILE
CONTINUED 20-30 KTS OF EFFECTIVE BULK SHEAR WILL PERSIST...THIS WILL
LIKELY BE INSUFFICIENT TO COMPENSATE FOR THE RELATIVE LACK OF
STEADILY DECREASING BUOYANCY...SO ANY PRIOR SEVERE WEATHER THREAT
SHOULD DIMINISH PRIOR TO MIDNIGHT. NONETHELESS...SOME SHOWERS AND
ISOLATED STORMS ARE APT TO CONTINUE THROUGHOUT THE NIGHT...AS THE
SYNOPTIC SURFACE FRONTAL -- WHICH SIGNIFICANTLY LAGS THE ONGOING
PRE-FRONTAL MCS/S...AND ASSOCIATED OUTFLOW THAT WILL LIKELY HAVE A
DIFFICULT TIME CRESTING THE BLUE RIDGE TODAY -- GRADUALLY SETTLES
INTO AT LEAST THE NORTHWEST PIEDMONT TOWARD SUNRISE. CLOUDY OR
MOSTLY SO...WITH LOWS IN LOWER 70S FOR MOST.
SATURDAY: THERE ARE MIXED SIGNALS WITH RESPECT TO CONVECTIVE
COVERAGE AND INTENSITY ON SATURDAY. ON ONE HAND...LOW LEVEL FORCING
SHOULD BE QUITE STRONG AS THE LOW LEVEL FRONTAL ZONE...DEEP THROUGH
AT LEAST H85...SETTLES SOUTHEASTWARD THROUGH ALL OF CENTRAL NC BY
EVENING - A CHANGE FROM THE EARLIER EXPECTATION THAT THE BOUNDARY
WOULD STALL OVERHEAD THROUGH EARLY NEXT WEEK. ON THE OTHER
HAND...HOWEVER...THE PRECEDING PASSAGE OF THE LEAD MID LEVEL TROUGH
AXIS THROUGH CENTRAL NC FRI NIGHT...AND ASSOCIATED TRAILING NEUTRAL
TO WEAKLY RISING HEIGHTS ALOFT...SUGGESTS DEEPER LAYER SUBSIDENCE
WILL BE IN PLACE OVERHEAD. GIVEN THE DEPTH AND VIGOR OF THE LOW
LEVEL FRONTAL ZONE...IN CONJUNCTION WITH LOW LCL/LFC HEIGHTS AMIDST
HIGH BL MOISTURE CHARACTERIZED BY WARM SECTOR SURFACE DEWPOINTS AOA
70 DEGREES AND TEMPERATURES IN THE 80S...WILL LEAN TOWARD A HIGHER
LIKELIHOOD OF SHOWERS AND STORMS...DESPITE THE DEEPER LAYER
SUBSIDENCE. WHILE PRECIPITATION CHANCES SHOULD DIMINISH FROM
NORTHWEST TO SOUTHEAST WITH TIME AND THE PASSAGE OF THE FRONTAL
ZONE...A FEW ANAFRONTAL SHOWERS MAY CONTINUE TO PERCOLATE ON THE
IMMEDIATE COOL SIDE OF THE BOUNDARY WHERE ISENTROPIC UPGLIDE AND
LINGERING...ALBEIT DIMINISHED WEAK INSTABILITY...WILL COINCIDE.
WHILE EFFECTIVE BULK SHEAR VALUES WILL INCREASE INTO THE 25 TO 40 KT
RANGE BY LATE AFTERNOON AND EVENING...IN ADVANCE OF A S/W TROUGH
FORECAST TO LIFT THROUGH THE MIDDLE ATLANTIC STATES...THIS BELT OF
STRONGER FLOW IS FORECAST TO LAG THE MODERATELY UNSTABLE WARM
SECTOR. AS SUCH...MULTI-CELL CONVECTIVE MODES WITH A PRIMARY THREAT
OF DAMAGING WINDS SHOULD DOMINATE...ALTHOUGH THERE MAY BE A RELATIVE
SWEET SPOT IN A NARROW CORRIDOR ROUGHLY FROM ROCKINGHAM TO RALEIGH
TO ROANOKE RAPIDS...WHERE MORE OPTIMAL VALUES OF SHEAR AND
INSTABILITY MAY CO-EXIST AND SUPPORT A CONDITIONAL THREAT OF BRIEF
SUPERCELLULAR STRUCTURES.
SAT NIGHT: DRY WITH POST-FRONTAL NORTH TO NORTHEASTERLY FLOW...WITH
LOWS IN THE 64 TO 70 DEGREE RANGE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 320 AM EDT...
SURFACE TROUGH FORECAST TO BE EAST AND SOUTHEAST OF CENTRAL NORTH
CAROLINA AT SUNRISE SUNDAY... BUT WITH SURFACE DEWPOINTS IN EXCESS
OF 65 DEGREES AND A BROAD UPPER TROUGH EXTENDING SOUTH INTO THE GULF
STATES... RAIN CHANCES WILL CONTINUE. PRECIPITABLE WATERS ROUGHLY
1.5 INCHES NORTHWEST TO 1.75 INCHES SOUTHWEST... WITH SURFACE BASED
CAPE IN EXCESS OF 2500 JOULES SOUTHEAST... TO NEAR 2000 NORTHWEST.
MID LEVEL WINDS OF 35 TO 45 KNOTS AND MIXING HEIGHTS ONLY TO 4000
FEET. THE AIR MASS IS PRIMED FOR A FEW SEVERE THUNDERSTORMS IN THE
AFTERNOON WITH DAMAGING WINDS THE MAIN THREAT. THE BIGGEST CONCERN
IS LACK OF A SIGNIFICANT TRIGGER OTHER THAN DAYTIME HEATING. HOWEVER
CONVECTIVE TRIGGER TEMPERATURES ARE A LOW 80 TO 85 DEGREES... AND
WILL RETAIN AFTERNOON POPS OF 50 TO 60 PERCENT.
LOSS OF HEATING SHOULD END MOST CONVECTION... BUT A THUNDERSTORM OR
TWO COULD PERSIST PAST MIDNIGHT IN THIS ENVIRONMENT.
THE UPPER TROUGH CONTINUES ITS SLOW APPROACH FROM THE WEST MONDAY.
THE MID LEVEL PRESSURE GRADIENT TIGHTENS WITH A DEEP LAYER OF
SOUTHWEST WINDS OF 30 TO 45 KNOTS... STRONGEST SOUTHEAST.
PRECIPITABLE WATERS PERHAPS EXCEEDING TWO INCHES SOUTHEAST. 850
MILLIBAR TROUGH WILL BE NEAR OR EAST OF HIGHWAY ONE... AND HIGHEST
RAIN CHANCES WILL BE IN THAT AREA MONDAY AFTERNOON. FORTY PERCENT
POPS NORTHWEST TO 50 SOUTHEAST WITH THE THREAT FOR DAMAGING WINDS
SIMILARLY HIGHER SOUTHEAST THAN NORTHWEST DUE TO HIGHER INSTABILITY
AND POTENTIAL ENERGY.
WINDS ALOFT BEGIN TO WEAKEN A BIT MONDAY NIGHT... WITH SOME DRYING
ALOFT IN THE WEST AFTER MIDNIGHT. UNLESS THERE IS SOME MINOR SHORT
WAVE FOR UPPER LEVEL SUPPORT... MOST CONVECTION SHOULD END IN THE
EVENING. A VERY FEW SHOWERS OR A THUNDERSTORM COULD PERSIST PAST
MIDNIGHT... MAINLY NEAR AND EAST OF HIGHWAY ONE.
AFTERNOON LOW LEVEL THICKNESSES ABOUT FIVE METERS BELOW CLIMATOLOGY
SUNDAY... AND TEN TO FIFTEEN METERS MONDAY. TEMPERATURES BELOW
NORMAL... WITH HIGH TEMPERATURES 80 TO 85 SUNDAY... LOW 80S MONDAY.
LOWS BELOW NORMAL IN SPITE OF CLOUDS... AT LOWER 60S NORTHWEST TO
MID 60S SOUTHEAST.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 340 PM FRIDAY...
ROUGH CONSENSUS IN BEGINNING TO SHEAR OUT THE UPPER TROUGH TO OUR
WEST TUESDAY AS IT LIFTS NORTHEAST... WITH THE ECMWF MORE AGGRESSIVE
THAN THE GFS IN THIS PROCESS. A WEAK SURFACE TROUGH FORECAST NEAR OR
EAST OF INTERSTATE 95... AND WILL PLACE HIGHEST RAIN CHANCES THERE.
30 PERCENT RAIN CHANCE WELL EAST... WHICH MAY PROVE TOO LOW. LESS
THAN ONE IN SEVEN ELSEWHERE.
SIGNIFICANT DIFFERENCES IN THE UPPER LEVEL PATTERN FOR WEDNESDAY AND
THURSDAY IN THE MODELS... AND FORECAST IS OF BELOW AVERAGE
CONFIDENCE. ROUGH AGREEMENT IN SOUTHWEST FLOW ALOFT. THE CURRENT
FORECAST OF SLIGHT AFTERNOON RAIN CHANCES IS A BIT BELOW CLIMATOLOGY
BUT WITHIN REASON GIVEN UNCERTAINTY.
AFTERNOON TEMPERATURES WILL BE FORECAST NEAR TO A TOUCH BELOW
CLIMATOLOGY AT LOW TO MID 80S. LOW TEMPERATURES LOWER 60S NORTHWEST
TO MID 60S ELSEWHERE.
&&
.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
AS OF 715 AM FRIDAY...
ASIDE FROM MAINLY MVFR FOG AT KRDU/KRWI/KFAY THIS MORNING...VFR
CONDITIONS ARE EXPECTED FOR THE MAJORITY OF THE 12Z TAF PERIOD.
HOWEVER...THE APPROACH OF A MID LEVEL TROUGH AND ASSOCIATED LIFT
WILL RESULT IN SCATTERED SHOWERS AND STORMS LATE THIS AFTERNOON INTO
TONIGHT...PARTICULARLY FROM KINT/KGSO TO KRDU/KFAY. THE BEST CHANCE
FOR THUNDER WILL BE IN THE 22-03Z TIME FRAME...WITH PRIMARILY JUST
SHOWERS THEREAFTER.
OUTLOOK...A COLD FRONT WILL SETTLE THROUGH CENTRAL NC WITH AN
ACCOMPANYING ENHANCED CHANCE OF SHOWERS AND STORMS ON SAT...FOLLOWED
BY DRY VFR CONDITIONS SAT NIGHT. THE BOUNDARY WILL RETREAT NORTHWARD
AND REMAIN IN THE VICINITY OF CENTRAL NC...AMIDST A MOIST AND
PERTURBED SOUTHWEST FLOW ALOFT...WITH A RENEWED THREAT OF SHOWERS
AND STORMS SUN-TUE.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS/SMITH
SHORT TERM...
LONG TERM...
AVIATION...MWS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1039 AM EDT FRI AUG 17 2012
.SYNOPSIS...
COLD FRONT PASSES THIS AFTERNOON INTO THIS EVENING. WEAK HIGH
PRESSURE OVER WEEKEND...WITH DISTURBANCE ALOFT PASSING SUNDAY.
ANOTHER HIGH PRESSURE BUILDS NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
1000AM UPDATE...
COLD FRONT AS OF 14Z LOCATED JUST NEAR CMH...TO ILN...DOWN THRU
CENTRAL KY. BEGINNING TO SEE FRONTAL BAND ORGANIZING ACROSS N KY
AND E OH. INITIAL CLEAR SKY ACROSS C AND E ZONES FILLING WITH
CLDS. LATEST HRRR SEEMS TO HAVE A GOOD HANDLE ON THINGS AND USED
IT FOR TIMING OF HIGHEST POPS. THINK THIS BAND WILL PROPAGATE E
AHEAD OF FRONT AS DAY WEARS ON...AFFECTING CENTRAL WV 16-18Z...AND
EXITING SW VA/WV MTNS BY 21Z. SPC HAS INSERTED SW VA AND WV MTN
COUNTIES IN SLIGHT RISK FOR THIS AFTN BUT GIVEN RAPID INCREASE IN
CLDS ACROSS THOSE AREAS...NOT SEEING MUCH OF A THREAT FOR SVR WITH
HRRR NOT SHOWING MUCH IN THE WAY OF SFC BASED INSTABILITY ALTHOUGH
RUC DOES PAINT DECENT CAPE VALUES ACROSS N WV MTNS EARLY THIS
AFTN. WILL LEAVE THUNDER IN ACROSS CENTRAL AND EASTERN ZONES. WITH
DEEPER MOISTURE EXODUS BY 21Z...WILL TAPER OFF POPS BUT STILL
LEAVE SCHC/LOW CHC TO ABOUT OH RVR WITH SFC FRONT STILL TO MOVE
THRU. WILL WATCH FOR WATER ACROSS S WV MTNS AND IN PARTICULAR SW
VA FOR POSSIBLE TRAINING THIS AFTN.
PREVIOUS DISCUSSION BELOW...
STILL A EVOLVING/DEVELOPING SITUATION FOR US TODAY...SO HOURLY
POPS...CLOUDS...AND TEMPERATURES DIFFICULT TO SAY THE LEAST.
STILL SEEING THE IMPRESSIVE SUPPORT FOR AUGUST FROM THE RIGHT REAR
OF A 250 MB JET MAX...PEAKING AROUND 18Z IN THE WV LOWLANDS...AND
INTO THE MOUNTAINOUS COUNTIES 21Z-00Z.
SO DESPITE THE MCS IN THE TN VALLEY STEALING THE SHOWER LAST
NIGHT...WILL TRY TO INCREASE POPS AGAIN BY 15Z IN THE OHIO RIVER
CORRIDOR...THEN STREAKING NE BY 18Z ALONG THE INTERSTATE 79
CORRIDOR SOUTH INTO THE SOUTHERN COAL FIELDS...THEN THROUGH THE
MOUNTAINOUS COUNTIES BY 21Z. PRIOR TO THAT...HAVE SOME SCATTERED
SHOWERS POSSIBLE TO START THE DAY IN THE OHIO RIVER VALLEY
COUNTIES...AND WILL BE SLOWER INTRODUCING EVEN CHANCE POPS CKB-EKN
DOWN TO BKW REGION.
WILL THE SLOWER ADVANCEMENT EAST...THE MOUNTAINOUS COUNTIES COULD
DEVELOP MORE CAPE AND INSTABILITY THIS AFTERNOON.
STILL MAY BE A FEW LEFTOVER SHOWERS BEHIND THE MID/UPPER LEVEL
SUPPORT ASSOCIATED WITH THE SURFACE FRONT. STILL HAVING THAT FRONT
NEAR CRW BY 00Z SATURDAY. WAS A BIT FASTER LOWERING POPS IN
SOUTHEAST OHIO THIS AFTERNOON.
WILL STILL HAVE TO WATCH OUR WET COUNTIES AROUND THE CENTRAL
MOUNTAINS AND IN THE SOUTHERN COAL FIELDS TODAY AND THIS EVENING FOR
ANY TRAINING...BUT WOULD BE PREMATURE TO POST ANY FLASH FLOOD WATCH
AT THIS HOUR.
THE DRIER AIR SHOULD WORK INTO THE MID OHIO VALLEY INCLUDING PKB
THIS EVENING...BUT MAY STRUGGLE TO PUSH PASS A EKN-CRW LINE. SO
HAVE LOW CONFIDENCE ON WHETHER CLOUDS WILL HOLD OR FOG WILL FORM IN
THOSE EASTERN AND SOUTHERN COUNTIES OVERNIGHT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
SHORT TERM SHOULD START OUT WITH ANY LINGERING POPS ENDING AS COLD
FRONT AND MOISTURE CONTINUE MOVING AWAY FROM CWA. SURFACE HIGH
PRESSURE WILL SLIDE BY TO THE NORTH FOR THE FIRST HALF OF THE
WEEKEND KEEPING THINGS PRETTY DRY. BOTH 00Z GFS AND NAM SHOWING A
VORT MAX/SHORTWAVE TROUGH ASSOCIATED WITH CLOSED UPPER LOW NEAR
HUDSON BAY AT THE END OF THE SHORT TERM PERIOD...IMPACTING MAINLY
THE MOUNTAINS SUNDAY AFTERNOON INTO SUNDAY NIGHT. BASED ON FAIR
AGREEMENT BETWEEN 00Z GFS AND ECMWF...ADDED ANOTHER ROUND OF
ISOLATED SHOWERS MONDAY AFTERNOON...MAINLY IN THE NORTHERN
MOUNTAINS...AS ANOTHER 500MB RIPPLE SLIDES THROUGH.
TEMPS SHOULD GENERALLY BE A BIT BELOW NORMAL INTO EARLY NEXT WEEK.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
DRY WEATHER AND PLEASANT TEMPERATURES WILL PREVAIL THROUGH THE END
OF THE WEEK.
SOME WARM AIR ADVECTION NOTICED AT H850 FROM 11C TO 14-16C FROM
THE GFS/ECMWF UNDER WEAK SOUTHERLY FLOW FROM WED THROUGH THE END
OF THE WEEK. THEREFORE...INCREASED TEMPS TO THE MID TO UPPER 80S
SIMILAR TO HPC AND GMOS FROM WEDNESDAY THROUGH END OF THE PERIOD.
USED HPC TEMPS...WITH SOME TWEAKS DAY 5 THROUGH DAY 7.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
NEAR 10Z...COLD FRONT NEAR TOL TO SE INDIANA...WEST OF CVG.
WITH THE MCS COMPLEX IN THE TN VLY STEALING THE OVERNIGHT SHOW...WAS
SLOWER IN INCREASING POPS AND DROPPING CEILINGS. HAVE SOME
SCATTERED SHOWERS...NO THUNDER...INTO OHIO RIVER COUNTIES THRU 14Z.
CEILINGS MOSTLY 4 TO 8 THSD FT.
STILL STRONG SUPPORT ALOFT PASSING DURING THE LATE MORNING AND EARLY
AFTERNOON. TRIED TO INCREASE POPS 14Z TO 16Z AND SPREAD RAPIDLY
NORTHEAST INTO THE CKB AND EKN AREA BY 16-19Z...THEN NUDGING EAST IN
THE MOUNTAINOUS COUNTIES BY 21Z...WHILE LOWERING POPS IN SOUTHEAST
OHIO AND THE PKB VCNTY. MOSTLY SHOWERS WITH EMBEDDED THUNDERSTORMS.
A FEW STRONGER THUNDERSTORMS POSSIBLE FURTHER EAST AND SOUTHEAST...
OVER SOUTHWESTERN VIRGINIA AND W VA INTO BKW-EKN VCNTY 18Z TO 00Z.
YET...THE SURFACE FRONT WILL STILL BE APPROACHING THE OHIO
RIVER...LIKELY NOT REACHING CRW UNTIL AROUND 00Z. SOME LESS
WIDESPREAD CONVECTION POSSIBLE WITH THE FRONT ITSELF.
HAVE CEILINGS 2 TO 4 THSD FT BKN AND VSBY NEAR 3 MILES IN THE
CONVECTION.
LOW CONFIDENCE IN WHAT HAPPENS TO THE CEILINGS THIS
EVENING...ESPECIALLY EKN TO CRW ON SOUTH. THE DRIER AIR SHOULD
PENETRATE THE CKB TO PKB CORRIDOR...BUT HAVE CEILINGS DEVELOPING AT
1 TO 2 THSD FT BKN AND VSBY 3 TO 5 MILES 00Z TO 03Z IN THE
SOUTH...WITH LOWER CONDITIONS POSSIBLE AFTER 03Z SATURDAY.
AFTER 06Z...FIGURING WIDESPREAD CEILINGS AOB 1 THSD FT BKN AND VSBY
1 TO 3 MILES EKN-CRW ON SOUTH INCLUDING THE SRN WV MOUNTAINS AROUND
BECKLEY. LOWER CEILINGS MAY BEGIN TO LIFT BFR 12Z SATURDAY EKN-CRW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SATURDAY...
FORECAST CONFIDENCE: LOW.
ALTERNATE SCENARIOS: THE TIMING AND THE AREAL COVERAGE OF THE
SHOWERS/THUNDERSTORMS TODAY WILL VARY. FOG AND LOW CLOUDS MAY FORM
QUICKER THAN FORECAST IN SOUTHERN WEST VIRGINIA TONIGHT.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY H M M M M H H H H H H H
HTS CONSISTENCY M M M H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H M M H H H H H L L
PKB CONSISTENCY M M H H H H H H H H H H
CKB CONSISTENCY H H M M M H H H H H H H
AFTER 12Z SATURDAY...
IFR POSSIBLE IN CEILINGS AND VSBY OVER SOUTHERN WEST VIRGINIA IN
POSSIBLE STRATUS AND/OR FOG.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...KTB/30
SHORT TERM...MZ
LONG TERM...ARJ
AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1007 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE AREA TODAY. HIGH
PRESSURE WILL MOVE OVER THE AREA ON SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
COLD FRONT EAST OF THE AREA AND SOME SHOWERS ARE BEHIND IT. THE
SHOWERS WILL MOVE OUT QUICKLY THIS MORNING. THE CLOUDS ARE
DECREASING QUICKLY. HOWEVER WITH THE UPPER TROF IN THE AREA TODAY
AND PLENTY OF MOISTURE...THE HRRR MODEL AND SEVERAL OTHER MODELS
INDICATE THAT SOME ISOLATED SHOWERS COULD OCCUR INLAND OF THE
LAKE. ADDED A 20 POP FOR THE AFTERNOON. NO THUNDER AT THIS TIME
BUT THIS WILL HAVE TO BE WATCHED. NO CHANGE IN THE HIGH TEMPERATURES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
MODELS CONTINUE IN GOOD AGREEMENT MOVING LARGE AREA OF HIGH PRESSURE
EAST OVER THE AREA ON SATURDAY. AT THE UPPER LEVELS LONG WAVE
TROUGH DIGS OVER THE GREAT LAKES AND REMAINS NEARLY STATIONARY
THROUGH PERIOD. CONDITIONS SHOULD REMAIN RELATIVELY DRY WITH TEMPS
ACTUALLY BELOW NORMAL.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
NO BIG CHANGE FROM PREVIOUS FORECASTS. MODELS SHOW MODERATING
TEMPERATURES AS AN UPPER TROF PULLS EAST AND HEIGHTS RISE ACROSS THE
LOWER GREAT LAKES AND OHIO VALLEY. AT THE SURFACE...HIGH PRESSURE
WILL CONTINUE ACROSS THE AREA...SHIFTING EAST LATE IN THE PERIOD BUT
CONTINUING TO INFLUENCE THE AREA. WILL HAVE HIGHS RISING THROUGH
THE 70S TO THE LOWER 80S BY THURSDAY. PRECIP CHANCES MOSTLY SLIGHT
CHANCES TO NIL.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
COLD FRONT MOVING EAST OF THE AREA THIS HOUR WITH MVFR CIGS ACROSS
MAINLY THE EAST PORTION OF THE AREA. VFR CIGS IN THE CENTRAL WITH
CLEARING NORTHWEST. LIGHT RAIN SHOWERS ALSO OCCURRING IN A BROKEN
LINE FROM BETWEEN MFD AND MNN TO THE ERIE AREA. CIGS WILL LIFT TO
VFR THIS MORNING EAST WHILE CLEARING WILL CONTINUE TO PUSH EAST
INTO THE CENTRAL HIGHLANDS THIS MORNING AND THEN EAST THIS
AFTERNOON. EXPECT VFR CONDITIONS OVERNIGHT ALTHOUGH NEAR DAWN
EXPECT PATCH MVFR FOG/MIST.
.OUTLOOK...VFR EXCEPT FOR A CHANCE OF MVFR CEILINGS EXTREME
NE OH/NW PA MONDAY AND TUESDAY MORNING.
&&
.MARINE...
WILL GO WITH A SMALL CRAFT ADVISORY FOR TODAY. COLD FRONT IS NOW
MOVING ACROSS THE LAKE WITH 15 TO 20 KNOT WINDS AHEAD OF THE
BOUNDARY...GUSTING INTO THE 20S. BEHIND THE FRONT WINDS TURN
NORTHWEST WHICH WILL BRING THE HIGHEST WAVES ONTO THE SOUGH SHORE OF
THE LAKE. CURRENTLY BUOYS ARE REPORTING 3 FOOT WAVES AND WOULD
EXPECT A CONTINUED BUILD THROUGH LATE MORNING BEFORE BEGINNING TO
DROP BACK AS WINDS DIMINISH. BROAD HIGH PRESSURE WILL BUILD IN
SATURDAY AND CONTINUE TO AFFECT THE LAKE THROUGH THE REMAINDER OF
THE FORECAST.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR
LEZ145>149.
&&
$$
SYNOPSIS...DJB
NEAR TERM...KIELTYKA
SHORT TERM...DJB
LONG TERM...TK
AVIATION...TK
MARINE...TK
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
155 AM EDT FRI AUG 17 2012
.SYNOPSIS...
COLD FRONT PASSES THIS AFTERNOON INTO THIS EVENING. WEAK HIGH
PRESSURE OVER WEEKEND...WITH DISTURBANCE ALOFT PASSING SUNDAY.
ANOTHER HIGH PRESSURE BUILDS NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
915 PM UPDATE. VERY DIFFICULT. IMPRESSIVE MCS DROPPING EAST
SOUTHEAST INTO WESTERN KENTUCKY AT TIME WILL SURELY DISRUPT THE
MODEL CONSENSUS OF TRYING TO REFOCUS CONVECTION NORTHWARD ALONG
FRONT LATER ON TONIGHT. HAVE ADJUSTED POPS OVERNIGHT TO RAISE POPS
IN THE WEST AND SOUTHWEST FOR EASTWARD EXTENSION OF THE DYING MCS BY
THAT TIME. IN TURN...WHILE KEEPING REDEVELOPMENT FURTHER NORTH AS
THE FRONT MAKES IT TO OUR CWA BORDER BY 12Z...HAVE CUT CAT POPS TO
LIKELY. THIS MAY STILL BE TOO GENEROUS...BUT DID NOT WANT TO MAKE
WHOLESALE CHANGES THIS FAR OUT. OTHERWISE...WILL CONTINUE PLAYING AN
EARLY MORNING BAND OF CONVECTION SURGING OUR AHEAD OF THE FRONT...
AND A BETTER AFTERNOON CONVECTIVE BAND WITH THE FRONT AS IT MOVES
ACROSS.
PREVIOUS DISCUSSION...
MORNING COMPLEX CONT TO WEAKEN AS IT RUNS IN TO DRY AIR IN MID
LVLS AND AWAY FROM COLD FRONT/UPR SUPPORT. RUC AND RAP DO INDICATE
A SLIGHT MOISTENING ACROSS PERRY/MORGAN 22-00Z WHICH MAY BE ENOUGH
FOR AN ISO SHRA/TSRA AS REMNANTS...AT LEAST ALOFT...MOVE ACROSS E
OH. THUS ELECTED TO CODE UP SCHC ACROSS PERRY DURING
AFOREMENTIONED TIME FRAME.
OTHERWISE WILL BE WAITING FOR APPROACH OF UPR TROF AND ASSOCIATED
SFC FRONT HEADING INTO TOMORROW. LIKED TIMING OF PREV FCST WHICH
IS IN GOOD AGREEMENT WITH NAM. LOOKS LIKE AREA WILL BE DEALING
WITH TWO POSSIBLE BANDS OF PCPN...PREFRONTAL BAND IN THE MORNING
FOLLOWED BY A ROUND OF CONVECTION MORE WITH ACTUAL FRONT. HAVE SFC
FRONT JUST ENTERING SE OH AT 12Z WITH PREFRONTAL BAND HAVING
TRAVERSED THRU SE OH/NE KY INTO CENTRAL WV...AIDED MORE BY DECENT
OMEGA ARND H7 AND LLVL WAA. EXPECT THIS TO FIZZLE OUT AS IT HEADS
INTO MTNS BY MID MORNING. WILL KEEP THUNDER IN GIVEN ELEVATED
INSTABILITY. MEANWHILE FRONT MAY SLOW DOWN BRIEFLY TOMORROW WITH
ANOTHER ORGANIZED BAND OF INITIALLY FRONTAL CONVECTION MOVING
ACROSS THE AREA AFTER A BRIEF BREAK FOLLOWING MORNING CONVECTION.
THIS LOOKS TO PROPAGATE OUT AHEAD OF BOUNDARY IN AFTN AND EXIT
MTNS BY 21Z AS DEEPER MOISTURE IS EXODUS. WILL HANG SOME LOW POPS
BACK A FEW HRS WITH SFC FRONT ONLY CROSSING OH RVR BY SAID TIME.
WILL GO WITH HIGHER NUMBERS TONIGHT WITH BL FLOW INCREASING LATE.
HIGHS TOMORROW TRICKY. WILL LEAN TOWARD LOWER NUMBERS FROM
GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
COLD FRONT EXPECTED TO BE EXIT THE EASTERN MOUNTAINS AT THE
BEGINNING OF THE PERIOD WITH PCPN DECREASING FROM CHANCE TO SLIGHT
CHANCE THROUGH 12Z SATURDAY. DEWPOINTS WILL LINGER INTO THE LOWER
60S EXTREME NORTHEAST...UPPER TO MID 50S EAST OF THE OH
RIVER...DROPPING TO THE LOW 50S ACROSS SOUTHEAST OH BY SATURDAY
MORNING.
HIGH PRESSURE BUILDS BEHIND THE FRONT WITH DRIER AIR TO PROVIDE
PLENTY OF SUNSHINE SATURDAY. WITH ABUNDANT LINGERING MOISTURE OVER
THE EASTERN MOUNTAINS...KEPT SLIGHT CHANCE FOR AFTERNOON SHOWERS.
WITH THE EXPECTED WIDESPREAD CLEARING SATURDAY AND SUNDAY
NIGHTS...DENSE FOG IS A GOOD BET OVER AREAS THAT RECEIVE RAIN AND
ALONG RIVER VALLEYS DUE TO NEAR CLAM FLOW.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
HIGH PRESSURE STRENGTHENS THROUGH MID WEEK PROVIDING MOSTLY CLEAR
SKIES AND NORMAL TEMPERATURES. HOWEVER...THE GFS SUGGEST UPPER LEVEL
SYNOPTIC LIFT ASSOCIATED WITH AND UPPER LEVEL JET...ALTHOUGH
MOISTURE IS LIMITED PER PWATS AROUND 0.75 INCHES...FEW SHOWERS COULD
DEVELOP ONCE AGAIN OVER THE EASTERN MOUNTAINS SUNDAY AFTERNOON.
OTHERWISE...DRY WEATHER AND PLEASANT TEMPERATURES WILL PREVAIL
THROUGH THE END OF THE WEEK.
SOME WARM AIR ADVECTION NOTICED AT H850 FROM 11C TO 14-16C FROM
THE GFS/ECMWF UNDER WEAK SOUTHERLY FLOW FROM WED THROUGH THE END
OF THE WEEK. THEREFORE...INCREASED TEMPS TO THE MID TO UPPER 80S
SIMILAR TO HPC AND GMOS FROM WEDNESDAY THROUGH END OF THE PERIOD.
USED HPC TEMPS...WITH SOME TWEAKS DAY 5 THROUGH DAY 7.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
PREFRONTAL TROF ALREADY DROPPING INTO SOUTHEAST OHIO 06Z TO 12Z.
YET...SURFACE FRONT FURTHER WEST. WITH THE MCS COMPLEX IN THE TN
VLY STEALING THE OVERNIGHT SHOW...WAS SLOWER IN INCREASING POPS AND
DROPPING CEILINGS. HAVE SOME SCATTERED SHOWERS...NO THUNDER...INTO
OHIO RIVER COUNTIES DURING THE PREDAWN HOURS. HAVE CEILINGS MOSTLY
5 TO 10 THSD FT BKN BY 10Z.
STILL STRONG SUPPORT ALOFT PASSING DURING THE LATE MORNING AND EARLY
AFTERNOON. TRIED TO INCREASE POPS 14Z TO 16Z AND SPREAD RAPIDLY
NORTHEAST INTO THE CKB AND EKN AREA BY 16-18Z...THEN NUDGING EAST IN
THE MOUNTAINOUS COUNTIES BY 21Z...WHILE LOWERING POPS IN SOUTHEAST
OHIO AND THE PKB VCNTY. YET...THE SURFACE FRONT WILL STILL BE
APPROACHING THE OHIO RIVER...LIKELY NOT REACHING CRW UNTIL AROUND
00Z. SOME LESS WIDESPREAD CONVECTION POSSIBLE WITH THE FRONT ITSELF.
HAVE CEILINGS 2 TO 4 THSD FT BKN AND VSBY NEAR 3 MILES IN THE
CONVECTION.
LOW CONFIDENCE IN WHAT HAPPENS TO THE CEILINGS THIS
EVENING...ESPECIALLY EKN TO CRW ON SOUTH. THE DRIER AIR SHOULD
PENETRATE THE CKB TO PKB CORRIDOR...BUT HAVE CEILINGS DEVELOPING AT
1 TO 2 THSD FT BKN AND VSBY 3 TO 5 MILES 00Z TO 03Z IN THE
SOUTH...WITH LOWER CONDITIONS POSSIBLE AFTER 03Z SATURDAY.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY...
FORECAST CONFIDENCE: LOW.
ALTERNATE SCENARIOS: THE TIMING AND THE AREAL COVERAGE OF THE
SHOWERS/THUNDERSTORMS TODAY WILL VARY. FOG AND LOW CLOUDS MAY FORM
AFTER FRIDAY EVENING THAN FORECAST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE FRI 08/17/12
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY H H H H H H H M M M H H
HTS CONSISTENCY H H H H H H M M M M H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L M M H H H H H H H H
PKB CONSISTENCY H H H H H H H M H H H H
CKB CONSISTENCY H H H H H H H H M M H H
AFTER 06Z SATURDAY...
IFR POSSIBLE IN CEILINGS AND VSBY OVER SOUTHERN WEST VIRGINIA IN
POSSIBLE STRATUS AND/OR FOG.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/ARJ/30
NEAR TERM...JMV/30
SHORT TERM...ARJ
LONG TERM...ARJ
AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1257 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT ACROSS THE WESTERN GREAT LAKES WILL MOVE EAST ACROSS
THE LOCAL AREA TONIGHT. THE FRONT WILL MOVE TO THE EAST COAST
FRIDAY ALLOWING HIGH PRESSURE TO BEGIN BUILDING OVER THE REGION
FROM THE WEST. THE HIGH IS EXPECTED TO LINGER OVER THE REGION
THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
COLD FRONT CONTINUES TO PUSH EAST INTO INDIANA THIS EVENING AND
WILL MOVE ACROSS THE FORECAST AREA LATER OVERNIGHT AND TUE
MORNING. RADAR SHOWING MOST OF CONVECTION IN MICHIGAN. MOST MODELS
SUGGESTING SOME ADDITIONAL CONVECTION DEVELOPING NEAR THE FRONT
AND MOVE INTO NRN OHIO OVERNIGHT...BUT WILL HAVE TO SEE GIVEN
THUNDERSTORM COMPLEX SOUTHWEST OF THE AREA. FOR NOW LEFT THE
CATEGORICAL POPS OVER THE AREA AS THINKING MOST LOCATIONS WILL SEE
AT LEAST A BRIEF PERIOD OF SHRA/TS WITH THE FRONTAL PASSAGE. MADE
SMALL ADJUSTMENTS TO TEMPS BUT NOTHING SIGNIFICANT FOR THE
OVERNIGHT WITH LOWER TO MID 60S ACROSS THE AREA.
PREVIOUS DISCUSSION...
THE AREA OF SHOWERS MOVING TOWARD NW OH CONTINUES TO BREAK UP BUT
HAVE STARTED TO SEE SOME NEW DEVELOPMENT IN FAR NE OH ALONG A LAKE
BREEZE BOUNDARY. THESE TRENDS WILL LIKELY CONTINUE FOR THE
REMAINDER OF THE AFTERNOON WITH AN INCREASE IN ACTIVITY IN THE
EAST AND A DECREASE IN THE WEST. HRRR AND CONVECTIVE SREF CONTINUE
TO SHOW ANOTHER LINE OF STORMS DEVELOPING JUST TO THE WEST OF THE
AREA TOWARD 00Z AHEAD OF AN APPROACHING COLD FRONT. THIS IS THE
LINE THAT WILL LIKELY BRING PRECIP TO THE ENTIRE AREA OVERNIGHT.
WILL CONTINUE WITH CATEGORICAL PRECIP CHANCES WITH MOST AREAS
SEEING UP TO A HALF INCH OF RAINFALL. THE PRECIP WILL END FROM
WEST TO EAST AFTER MIDNIGHT AS THE FRONT PULLS OUT. THICK CLOUDS
HAVE OVERSPREAD THE AREA AND THE THREAT FOR SEVERE WEATHER APPEARS
MINIMAL. BETTER INSTABILITY REMAINS TO THE SW AND THAT IS WHERE
ANY SEVERE WEATHER WILL LIKELY OCCUR.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
THE COLD FRONT WILL BE GONE BY DAYBREAK AND MOST OF THE PRECIP
ALONG WITH IT. COULD SEE SOME SHOWERS IN THE EAST AND SOUTH
THROUGH MIDDAY BUT AFTER THAT IT SHOULD BE TOO DRY FOR MORE
PRECIP. 850 MB TEMPS WILL DIP TO AROUND PLUS 8 BY FRIDAY EVENING
SO THIS WILL BE A COLD AIRMASS. WILL LIKELY SEE A FAIR AMOUNT OF
LAKE EFFECT STRATO CU THROUGH SATURDAY. SOME INDICATION FROM THE
MODELS OF ANOTHER WEAK FRONT APPROACHING FROM THE NORTH LATE
SUNDAY AND SUNDAY NIGHT. WILL GO WITH A VERY SMALL MENTION OF
SHOWERS IN THE FAR NORTH BUT REALLY DON`T THINK THIS WILL BE A BIG
DEAL. TEMPS WILL AVERAGE WELL BELOW NORMAL AND LATER SHIFTS WILL
HAVE TO WATCH FOR POSSIBLE 40S FOR LOWS SUNDAY MORNING. HAVE USED
A BLEND OF GUIDANCE DURING THE PERIOD.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
INITIALLY LONG RANGE PART OF FORECAST SHOULD START OFF COOL AND
SOMEWHAT CLOUD. THE BIG QUESTION IS WHETHER THE UPPER TROF OVER THE
AREA WILL CAUSE ENOUGH FORCING TO PRODUCE A FEW SHRA...ESPECIALLY IN
THE SNOWBELT OR WHETHER SURFACE HIGH PRESSURE WILL KEEP THINGS DRY.
PREFERENCE IS TO CARRY AT LEAST A SLIGHT CHANCE FOR THE NE PART OF
THE AREA MON THEN GO DRY TUE AS THE UPPER TROF WEAKENS AND SHIFT
EAST.
WED LOOKS DRY AS TEMPS WARM BACK TO NORMAL. THE MODELS DIFFER BY THU
SO MUCH GREATER UNCERTAINTY IN OVERALL FORECAST. THUS FORECAST WILL
LARGELY BE INFLUENCED BY BEST COLLABORATION WITH SURROUNDING WFO`S.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
COLD FRONT MOVING INTO THE NORTHWEST CORNER OF OHIO THIS HOUR WITH
LIGHT RAIN SHOWERS IN VICINITY OF THE BOUNDARY. NOT COMPLETELY OUT
OF THE QUESTION TO GET THUNDER TO DEVELOP OVERNIGHT WITH THE FRONT
ACROSS THE REGION BUT FOR NOW WILL LEAVE OUT. CONDITIONS ARE VFR
ON THE EAST SIDE OF THE FRONT WITH PATCHY MVFR VISIBILITIES AND
CIGS IN LIGHT RAIN BEHIND. FRIDAY EXPECT MVFR CONDITIONS ACROSS
MUCH OF THE AREA IMPROVING TO VFR DURING THE LATE MORNING AND
EARLY AFTERNOON FROM THE WEST.
.OUTLOOK...VFR EXCEPT FOR A CHANCE OF MVFR CEILINGS EXTREME
NE OH/NW PA MONDAY AND TUESDAY MORNING.
&&
.MARINE...
COLD FRONT WILL MOVE INTO THE CENTRAL GREAT LAKES TONIGHT. EXPECT TO
SEE SOUTHWEST WINDS TO REMAIN IN THE 10 TO 20 KNOT RANGE. HOWEVER
THE EASTERN HALF OF THE LAKE COULD SEE SLIGHTLY HIGHER FOR A COUPLE
HOURS JUST AHEAD OF THE FRONT AFTER MIDNIGHT. WILL THEN AWAIT THE
WIND SHIFT TO CLEAR LAKE ERIE NEAR OR SHORTLY AFTER SUNRISE.
NORTHWESTERLY WINDS MAY BE JUST STRONG ENOUGH WITH THE LONGER FETCH
TO PROVIDE SMALL CRAFT CONDITIONS FOR THE EASTERN HALF TO TWO THIRDS
OF THE LAKE INTO FRIDAY AFTERNOON. WILL LET THE NEXT SHIFT MONITOR
THIS POTENTIAL OVERNIGHT TO DECIDE IF WE WILL REACH THE CRITERIA.
HIGH PRESSURE WILL THEN CONTROL THE LAKE WITH A LIGHT WEST TO
NORTHWEST WIND EXPECTED THROUGH THE WEEKEND. SOUTHWESTERLY WINDS
SHOULD RETURN BY MONDAY AFTERNOON AND SHOULD PERSIST INTO TUESDAY
AHEAD OF THE NEXT COLD FRONT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...ABE/KUBINA
SHORT TERM...KUBINA
LONG TERM...ADAMS
AVIATION...TK
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
313 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL TRAVERSE THE AREA TODAY ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL STALL OUT JUST
OFFSHORE NEW ENGLAND...AND EXTEND SOUTHWARD ALONG THE MID-ATLANTIC
PIEDMONT INTO SATURDAY. AN ANOMALOUS UPPER LEVEL TROUGH WILL
EVOLVE OVER THE EASTERN HALF OF THE NATION THROUGH EARLY NEXT
WEEK...RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
WEAKENING COLD FRONT PUSHING INTO CENTRAL PA THIS MORNING. MOST
AREAS ALONG THE ALLEGHENY FRONT SAW A FEW HOURS OF LIGHT TO
MODERATE RAIN SHOWERS. A FEW POCKETS OF MODERATE TO BRIEFLY HEAVY
RAINFALL HAVE SPROUTED ALONG THE FRONT...MOST CONCENTRATED IN THE
LAUREL HIGHLANDS WHERE OROGRAPHIC ENHANCEMENT HAS TAKEN
PLACE...ALONG WITH GREATER PROXIMITY TO DEEPER MOISTURE AND CAPES.
FAR SOUTHEAST PA MAY BE ABLE TO MUSTER A FEW TO SEVERAL HUNDRED
J/KG*2 CAPES THIS AFTERNOON...WITH SOME T BECOMING EMBEDDED IN THE
MAIN LINE AND PERHAPS ISOLATED CELLS FORMING AHEAD OF THE LINE.
SEVERE THREAT REMAINS LOW HOWEVER. WITH THE FRONT TAKING ITS TIME
CROSSING THE CENTRAL MOUNTAINS THIS AFTERNOON... RAIN MAY NOT REACH
FAR SOUTHEAST COUNTIES UNTIL EARLY EVENING. LATEST HRRR UPDATE
VIA COSPA DEPICTS SLOW INTENSIFICATION OF THE CURRENT LINE OF
SHOWERS AS IT EXITS THE CENTRAL MOUNTAINS AND HEADS INTO THE LOWER
SUSQUEHANNA RIVER VALLEY THIS EVENING.
MUCH DRIER AIR WILL BE DIRECTED INTO THE AREA IN THE WAKE OF THE
COLD FRONT TONIGHT AND EARLY SATURDAY...WITH PCPN ENDING ACRS THE N/W
HALF OF THE CWA THIS EVE. AS THE CLOSED LOW BECOMES NEARLY STATIONARY
OVER JAMES BAY..THE COLD FRONT WILL SLOW ITS EWD PROGRESSION AND
REMAIN A FOCUS FOR SHOWERS/ISOLD TSTMS ACRS THE SERN 1/2 OF THE
CWA THRU LATE TNT AND ERLY SAT.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
BROAD CYC FLOW ALOFT WILL DOMINATE THE UPPER LEVEL PATTERN FOR THE
FORESEEABLE FUTURE WITH DRIER LLVL AND QUITE COMFORTABLE STRETCH
OF WEATHER EXPECTED ACROSS THE REGION THROUGH THE WEEKEND AND MUCH
OF NEXT WEEK. SHOWERS WILL EXIT MY SOUTHEAST COUNTIES AROUND 12Z
SAT WITH IMPROVING CONDS SLATED BY AFTERNOON THANKS TO WEAK HIGH
PRESSURE BUILDING OVER CENTRAL PA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MDL DATA INDICATES THE DEVELOPING UPPER-LEVEL TROUGH OVER ERN
NORTH AMERICA WILL UNDERGO ADDITIONAL AMPLIFICATION SUN-MON...AS
ENERGY DROPS SWD FM THE NRN PLAINS AND DIGS/SHARPENS THE TROUGH.
THE 12Z OPERATIONAL GFS AND ECMWF FORM A WEAK SFC LOW OVR THE SRN
MID-ATLC COAST BY MON. WENT WITH LOW-END CHC POPS...MAINLY FM
LATE SUNDAY INTO THE DAY ON MONDAY.
12Z GEFS SHOWS 500MB HEIGHTS OF -1 TO -2SD THROUGH THE MIDDLE OF
NEXT WEEK...WHICH WILL KEEP TEMPERATURES COOLER THAN NORMAL.
THE UPPER-LEVEL TROUGH WILL GRADUALLY LIFT NORTHWARD LATE IN THE
WEEK...ALLOWING THE FLOW TO BECOME MORE ZONAL. RISING HEIGHTS AND
RETURN FLOW SHOULD ALLOW FOR A MODERATION IN TEMPS BACK TO AT
LEAST SEASONAL NORMALS BY THE END OF NEXT WEEK.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
LINE OF SHOWERS PRESSING EASTWARD THIS AFTERNOON AND EVENING WITH
EMBEDDED ISOLATED T OVER SOUTHEASTERN PA TERMINALS. LEFT MENTION
OF T OUT GIVEN LOW PROB AT ANY GIVEN AIRFIELD. SHOWERS WILL END
THIS EVENING OVER THE WEST AND EARLY SAT MORNING ACROSS THE
SOUTHEAST.
COLD ADVECTION AND CYCLONIC FLOW ALOFT COUPLED WITH LOW LEVEL
MOISTURE LEFT OVER FROM TODAYS PRECIPITATION WILL LIKELY SPELL
SOME OVERNIGHT STRATUS AND FOG OVERNIGHT NIGHT WITH MVFR
CONDITIONS...AND SOME IFR IN THE NORTHERN AND WESTERN MOUNTAINS.
DRIER AND COOLER AIR WORKS IN FOR THE WEEKEND...AND EARLY NEXT WEEK.
OUTLOOK...
SAT-TUE...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR
SHORT TERM...DEVOIR
LONG TERM...EVANEGO
AVIATION...JUNG/DEVOIR/TYBURSKI
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
253 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL TRAVERSE THE AREA TODAY ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL STALL OUT JUST
OFFSHORE NEW ENGLAND...AND EXTEND SOUTHWARD ALONG THE MID-ATLANTIC
PIEDMONT INTO SATURDAY. AN ANOMALOUS UPPER LEVEL TROUGH WILL
EVOLVE OVER THE EASTERN HALF OF THE NATION THROUGH EARLY NEXT
WEEK...RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAKENING COLD FRONT PUSHING INTO CENTRAL PA THIS MORNING. MOST
AREAS ALONG THE ALLEGHENY FRONT SAW A FEW HOURS OF LIGHT TO
MODERATE RAIN SHOWERS. A FEW POCKETS OF MODERATE TO BRIEFLY HEAVY
RAINFALL HAVE SPROUTED ALONG THE FRONT...MOST CONCENTRATED IN THE
LAUREL HIGHLANDS WHERE OROGRAPHIC ENHANCEMENT HAS TAKEN
PLACE...ALONG WITH GREATER PROXIMITY TO DEEPER MOISTURE AND CAPES.
FAR SOUTHEAST PA MAY BE ABLE TO MUSTER A FEW TO SEVERAL HUNDRED
J/KG*2 CAPES THIS AFTERNOON...WITH SOME T BECOMING EMBEDDED IN THE
MAIN LINE AND PERHAPS ISOLATED CELLS FORMING AHEAD OF THE LINE.
SEVERE THREAT REMAINS LOW HOWEVER. WITH THE FRONT TAKING ITS TIME
CROSSING THE CENTRAL MOUNTAINS THIS AFTERNOON... RAIN MAY NOT REACH
FAR SOUTHEAST COUNTIES UNTIL EARLY EVENING. LATEST HRRR UPDATE
VIA COSPA DEPICTS SLOW INTENSIFICATION OF THE CURRENT LINE OF
SHOWERS AS IT EXITS THE CENTRAL MOUNTAINS AND HEADS INTO THE LOWER
SUSQUEHANNA RIVER VALLEY THIS EVENING.
MUCH DRIER AIR WILL BE DIRECTED INTO THE AREA IN THE WAKE OF THE
COLD FRONT TONIGHT AND EARLY SATURDAY...WITH PCPN ENDING ACRS THE N/W
HALF OF THE CWA THIS EVE. AS THE CLOSED LOW BECOMES NEARLY STATIONARY
OVER JAMES BAY..THE COLD FRONT WILL SLOW ITS EWD PROGRESSION AND
REMAIN A FOCUS FOR SHOWERS/ISOLD TSTMS ACRS THE SERN 1/2 OF THE
CWA THRU LATE TNT AND ERLY SAT.
&&
.SHORT TERM /SATURDAY/...
BROAD CYC FLOW ALOFT WILL DOMINATE THE UPPER LEVEL PATTERN FOR THE
FORESEEABLE FUTURE WITH DRIER LLVL AND QUITE COMFORTABLE STRETCH
OF WEATHER EXPECTED ACROSS THE REGION THROUGH THE WEEKEND AND MUCH
OF NEXT WEEK. SHOWERS WILL EXIT MY SOUTHEAST COUNTIES AROUND 12Z
SAT WITH IMPROVING CONDS SLATED BY AFTERNOON THANKS TO WEAK HIGH
PRESSURE BUILDING OVER CENTRAL PA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MDL DATA INDICATES THE DEEP UPPER LEVEL TROUGH WILL UNDERGO
ADDITIONAL AMPLIFICATION SUN-MON...AS SECONDARY S/W DROPS SWD FM
THE NRN PLAINS AND DIGS/SHARPENS THE TROUGH INTO THE LWR MS/TN
VLYS. IN RESPONSE TO HEIGHT FALLS AND ENHANCED UPPER LEVEL
DIVERGENCE VIA STRENGTHENING RT ENTRANCE REGION JET DYNAMICS...THE
ECMWF/CANADIAN FORM A LOW OVR THE SRN MID-ATLC COAST BY 12Z MON.
THE GFS HINTS AT THIS IDEA BUT IS NOT AS WELL-DEVELOPED WITH ITS
SFC LOW. CONSENSUS BLEND SUPPORTS LOW-END CHC POPS MAINLY FM SUN
NGT INTO THE DAY ON MONDAY.
THE HIGH-AMPLITUDE UPPER TROUGH EAST OF THE MS RIVER WILL REMAIN
Q-STNRY AND SLOWLY DEAMPLIFY INTO THE SECOND HALF OF THE PD TUE-
THURS. THIS PD SHOULD FEATURE MAINLY FAIR/DRY WEATHER WITH SFC
HIGH PRES IN CONTROL. RISING HEIGHTS AND GRADUAL RETURN FLOW WILL
LKLY ALLOW FOR A MODERATION IN TEMPS BACK TO AT LEAST SEASONAL
NORMALS...IF NOT ABOVE NORMAL.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
LINE OF SHOWERS PRESSING EASTWARD THIS AFTERNOON AND EVENING WITH
EMBEDDED ISOLATED T OVER SOUTHEASTERN PA TERMINALS. LEFT MENTION
OF T OUT GIVEN LOW PROB AT ANY GIVEN AIRFIELD. SHOWERS WILL END
THIS EVENING OVER THE WEST AND EARLY SAT MORNING ACROSS THE
SOUTHEAST.
COLD ADVECTION AND CYCLONIC FLOW ALOFT COUPLED WITH LOW LEVEL
MOISTURE LEFT OVER FROM TODAYS PRECIPITATION WILL LIKELY SPELL
SOME OVERNIGHT STRATUS AND FOG OVERNIGHT NIGHT WITH MVFR
CONDITIONS...AND SOME IFR IN THE NORTHERN AND WESTERN MOUNTAINS.
DRIER AND COOLER AIR WORKS IN FOR THE WEEKEND...AND EARLY NEXT WEEK.
OUTLOOK...
SAT-TUE...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR
SHORT TERM...DEVOIR
LONG TERM...
AVIATION...DEVOIR/TYBURSKI
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
135 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL TRAVERSE THE AREA TODAY ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL STALL OUT JUST
OFFSHORE NEW ENGLAND...AND EXTEND SOUTHWARD ALONG THE MID-ATLANTIC
PIEDMONT INTO SATURDAY. AN ANOMALOUS UPPER LEVEL TROUGH WILL
EVOLVE OVER THE EASTERN HALF OF THE NATION THROUGH EARLY NEXT
WEEK...RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAKENING COLD FRONT PUSHING INTO MY NORTHWEST COUNTIES LATE THIS
MORNING. A FEW HOURS OF LIGHT TO MODERATE RAIN SHOWERS ARE ALL
THIS SYSTEM CAN MUSTER TO THIS POINT...AND EXPECT THAT TO BE THE
CASE IN THE SFC HEATING CHALLENGED ENVIRONMENT ACROSS CENTRAL PA
AS WELL. FAR SOUTHEAST PA MAY BE ABLE TO MUSTER A FEW HUNDRED J OF
CAPE THIS AFTERNOON...WITH SOME T BECOMING EMBEDDED IN THE MAIN
LINE AND PERHAPS ISOLATED CELLS FORMING AHEAD OF THE LINE. SEVERE
THREAT REMAINS LOW HOWEVER...AND THE FRONT WILL TAKE ITS TIME
CROSSING THE CENTRAL MOUNTAINS THIS AFTERNOON. RAIN MAY NOT REACH
ALL OF MY SOUTHEASTERN COUNTIES BY 00Z SAT. AS PREVIOUSLY MENTIONED...
IF THE OUTLIER SOLUTION OF BETTER INSTABILITY WERE TO BE REALIZED...
THE CONVECTIVE ENVIRONMENT COULD CONCEIVABLY SUPPORT SEMI-
ORGANIZED STRUCTURES WITH PERHAPS A MIX OF PULSE AND MULTICELL
STORM MODES. THE BEST CHC FOR STG STORMS IS LKLY OVR THE ERN 1/2
OF THE CWA GIVEN LESS CLOUDS/BETTER HEATING. LATEST HRRR UPDATE
VIA COSPA DEPICTS SLOW INTENSIFICATION OF THE CURRENT LINE OF
SHOWERS AS IT CROSSES THE CENTRAL MOUNTAINS EARLY THIS
AFTERNOON...AND APPROACHES THE LOWER SUSQ LATE THIS AFTERNOON AND
EVENING.
MUCH DRIER AIR WILL BE DIRECTED INTO THE AREA IN THE WAKE OF THE
COLD FRONT...WITH PCPN ENDING ACRS THE N/W HALF OF THE CWA BY LATE
AFTN/EARLY EVE. AS THE CLOSED LOW BECOMES NEARLY STATIONARY OVER
JAMES BAY..THE COLD FRONT WILL SLOW ITS EWD PROGRESSION AND REMAIN
A FOCUS FOR SHOWERS/ISOLD TSTMS ACRS THE SERN 1/2 OF THE CWA THRU
TNT. THE 17/00Z MDLS SHOW ONE OR MORE WAVES DEVELOPING ALONG THE
FNT AS IT SLOWS DOWN OVR ERN PA. THE NAM IS THE MOST AGGRESSIVE
WITH THIS FEATURE FOLLOWED BY THE CANADIAN. THE 00Z GFS IS MORE
PROGRESSIVE AND LOOKS SIMILAR TO THE UKMET/ECMWF. THEREFORE HAVE
INCREASED POPS INTO LKLY RANGE FOR THE FAR SE ZONES AFT 00Z.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
THE LG SCALE PATTERN WILL CONTINUE TO BE DOMINATED BY BROAD CYC
FLOW ALOFT ASSOCD WITH DEEP UPPER LEVEL TROUGH EXPANDING OVER THE
ERN CONUS...WITH HEIGHTS FCST TO REACH 3 SD BELOW NORMAL AT 500MB
OVER THE MS/OH VLYS. MUCH OF THE REGION WILL BE UNDER THE
INFLUENCE OF RELATIVELY COOL AND ABNORMALLY DRY SFC HIGH PRES
CENTERED OVR THE SRN GRT LKS/MIDWEST. THE FORECAST CHALLENGE FOR
D2 REVOLVES AROUND THE SLOWING/STALLING COLD FRONT OVR THE MID-
ATLC PIEDMONT...WHICH SHOULD SLOWLY DRIFT EWD TO THE COAST BY THE
END OF THE PD. THE NAM/GEM CONTINUE TO BE NORTH OF OTHER SOLUTIONS
AND KEEP PCPN GOING OVR SE PA INTO SAT EVE. WILL EMPLOY A MIDDLE
GROUND APPROACH AND KEEP LOW POPS GOING ACRS THE FAR SERN ZONES
THRU THE FIRST HALF OF D2. FCST TEMPS WILL AVG BELOW NORMAL ON
SAT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MDL DATA INDICATES THE DEEP UPPER LEVEL TROUGH WILL UNDERGO
ADDITIONAL AMPLIFICATION SUN-MON...AS SECONDARY S/W DROPS SWD FM
THE NRN PLAINS AND DIGS/SHARPENS THE TROUGH INTO THE LWR MS/TN
VLYS. IN RESPONSE TO HEIGHT FALLS AND ENHANCED UPPER LEVEL
DIVERGENCE VIA STRENGTHENING RT ENTRANCE REGION JET DYNAMICS...THE
ECMWF/CANADIAN FORM A LOW OVR THE SRN MID-ATLC COAST BY 12Z MON.
THE GFS HINTS AT THIS IDEA BUT IS NOT AS WELL-DEVELOPED WITH ITS
SFC LOW. CONSENSUS BLEND SUPPORTS LOW-END CHC POPS MAINLY FM SUN
NGT INTO THE DAY ON MONDAY.
THE HIGH-AMPLITUDE UPPER TROUGH EAST OF THE MS RIVER WILL REMAIN
Q-STNRY AND SLOWLY DEAMPLIFY INTO THE SECOND HALF OF THE PD TUE-
THURS. THIS PD SHOULD FEATURE MAINLY FAIR/DRY WEATHER WITH SFC
HIGH PRES IN CONTROL. RISING HEIGHTS AND GRADUAL RETURN FLOW WILL
LKLY ALLOW FOR A MODERATION IN TEMPS BACK TO AT LEAST SEASONAL
NORMALS...IF NOT ABOVE NORMAL.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AREA OF RAIN SHOWERS ASSOCIATED WITH A COLD FRONT MOVING THROUGH
THE REGION CURRENTLY STRETCHES FROM KBFD SOUTH THROUGH KJST AND
KAOO. SOME HEAVIER SHOWERS BEGINNING TO SHOW UP ON RADAR SOUTH OF
KAOO BUT NO LIGHTNING OCCURING.
EXPECT THE LINE OF SHOWERS TO PROGRESS EAST THROUGH THE LATE
AFTERNOON. ANY CONVECTION SHOULD BE CONFINED TO THE SOUTHEAST
PORTION OF THE STATE THIS AFTERNOON. LEFT THE MENTION OF TSRA OUT
OF ALL BUT KMDT AND KLNS FOR THE REMAINDER OF THE INTIAL PERIOD.
COLD ADVECTION AND CYCLONIC FLOW ALOFT COUPLED WITH LOW LEVEL
MOISTURE LEFT OVER FROM TODAYS PRECIPITATION WILL LIKELY SPELL
SOME OVERNIGHT STRATUS AND FOG FRIDAY NIGHT WITH MVFR
CONDITIONS...AND SOME IFR IN THE NORTHERN AND WESTERN MOUNTAINS.
DRIER AND COOLER AIR WORKS IN FOR THE WEEKEND...AND EARLY NEXT WEEK.
OUTLOOK...
SAT-TUE...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...DEVOIR/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...JUNG/TYBURSKI
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1117 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL TRAVERSE THE AREA TODAY ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL STALL OUT JUST
OFFSHORE NEW ENGLAND...AND EXTEND SOUTHWARD ALONG THE MID-ATLANTIC
PIEDMONT INTO SATURDAY. AN ANOMALOUS UPPER LEVEL TROUGH WILL
EVOLVE OVER THE EASTERN HALF OF THE NATION THROUGH EARLY NEXT
WEEK...RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAKENING COLD FRONT PUSHING INTO MY NORTHWEST COUNTIES LATE THIS
MORNING. A FEW HOURS OF LIGHT TO MODERATE RAIN SHOWERS ARE ALL
THIS SYSTEM CAN MUSTER TO THIS POINT...AND EXPECT THAT TO BE THE
CASE IN THE SFC HEATING CHALLENGED ENVIRONMENT ACROSS CENTRAL PA
AS WELL. FAR SOUTHEAST PA MAY BE ABLE TO MUSTER A FEW HUNDRED J OF
CAPE THIS AFTERNOON...WITH SOME T BECOMING EMBEDDED IN THE MAIN
LINE AND PERHAPS ISOLATED CELLS FORMING AHEAD OF THE LINE. SEVERE
THREAT REMAINS LOW HOWEVER...AND THE FRONT WILL TAKE ITS TIME
CROSSING THE CENTRAL MOUNTAINS THIS AFTERNOON. RAIN MAY NOT REACH
ALL OF MY SOUTHEASTERN COUNTIES BY 00Z SAT. AS PREVIOUSLY MENTIONED...
IF THE OUTLIER SOLUTION OF BETTER INSTABILITY WERE TO BE REALIZED...
THE CONVECTIVE ENVIRONMENT COULD CONCEIVABLY SUPPORT SEMI-
ORGANIZED STRUCTURES WITH PERHAPS A MIX OF PULSE AND MULTICELL
STORM MODES. THE BEST CHC FOR STG STORMS IS LKLY OVR THE ERN 1/2
OF THE CWA GIVEN LESS CLOUDS/BETTER HEATING. LATEST HRRR UPDATE
VIA COSPA DEPICTS SLOW INTENSIFICATION OF THE CURRENT LINE OF
SHOWERS AS IT CROSSES THE CENTRAL MOUNTAINS EARLY THIS
AFTERNOON...AND APPROACHES THE LOWER SUSQ LATE THIS AFTERNOON AND
EVENING.
MUCH DRIER AIR WILL BE DIRECTED INTO THE AREA IN THE WAKE OF THE
COLD FRONT...WITH PCPN ENDING ACRS THE N/W HALF OF THE CWA BY LATE
AFTN/EARLY EVE. AS THE CLOSED LOW BECOMES NEARLY STATIONARY OVER
JAMES BAY..THE COLD FRONT WILL SLOW ITS EWD PROGRESSION AND REMAIN
A FOCUS FOR SHOWERS/ISOLD TSTMS ACRS THE SERN 1/2 OF THE CWA THRU
TNT. THE 17/00Z MDLS SHOW ONE OR MORE WAVES DEVELOPING ALONG THE
FNT AS IT SLOWS DOWN OVR ERN PA. THE NAM IS THE MOST AGGRESSIVE
WITH THIS FEATURE FOLLOWED BY THE CANADIAN. THE 00Z GFS IS MORE
PROGRESSIVE AND LOOKS SIMILAR TO THE UKMET/ECMWF. THEREFORE HAVE
INCREASED POPS INTO LKLY RANGE FOR THE FAR SE ZONES AFT 00Z.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
THE LG SCALE PATTERN WILL CONTINUE TO BE DOMINATED BY BROAD CYC
FLOW ALOFT ASSOCD WITH DEEP UPPER LEVEL TROUGH EXPANDING OVER THE
ERN CONUS...WITH HEIGHTS FCST TO REACH 3 SD BELOW NORMAL AT 500MB
OVER THE MS/OH VLYS. MUCH OF THE REGION WILL BE UNDER THE
INFLUENCE OF RELATIVELY COOL AND ABNORMALLY DRY SFC HIGH PRES
CENTERED OVR THE SRN GRT LKS/MIDWEST. THE FORECAST CHALLENGE FOR
D2 REVOLVES AROUND THE SLOWING/STALLING COLD FRONT OVR THE MID-
ATLC PIEDMONT...WHICH SHOULD SLOWLY DRIFT EWD TO THE COAST BY THE
END OF THE PD. THE NAM/GEM CONTINUE TO BE NORTH OF OTHER SOLUTIONS
AND KEEP PCPN GOING OVR SE PA INTO SAT EVE. WILL EMPLOY A MIDDLE
GROUND APPROACH AND KEEP LOW POPS GOING ACRS THE FAR SERN ZONES
THRU THE FIRST HALF OF D2. FCST TEMPS WILL AVG BELOW NORMAL ON
SAT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MDL DATA INDICATES THE DEEP UPPER LEVEL TROUGH WILL UNDERGO
ADDITIONAL AMPLIFICATION SUN-MON...AS SECONDARY S/W DROPS SWD FM
THE NRN PLAINS AND DIGS/SHARPENS THE TROUGH INTO THE LWR MS/TN
VLYS. IN RESPONSE TO HEIGHT FALLS AND ENHANCED UPPER LEVEL
DIVERGENCE VIA STRENGTHENING RT ENTRANCE REGION JET DYNAMICS...THE
ECMWF/CANADIAN FORM A LOW OVR THE SRN MID-ATLC COAST BY 12Z MON.
THE GFS HINTS AT THIS IDEA BUT IS NOT AS WELL-DEVELOPED WITH ITS
SFC LOW. CONSENSUS BLEND SUPPORTS LOW-END CHC POPS MAINLY FM SUN
NGT INTO THE DAY ON MONDAY.
THE HIGH-AMPLITUDE UPPER TROUGH EAST OF THE MS RIVER WILL REMAIN
Q-STNRY AND SLOWLY DEAMPLIFY INTO THE SECOND HALF OF THE PD TUE-
THURS. THIS PD SHOULD FEATURE MAINLY FAIR/DRY WEATHER WITH SFC
HIGH PRES IN CONTROL. RISING HEIGHTS AND GRADUAL RETURN FLOW WILL
LKLY ALLOW FOR A MODERATION IN TEMPS BACK TO AT LEAST SEASONAL
NORMALS...IF NOT ABOVE NORMAL.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
BAND OF SCATTERED SHOWERS STILL REMAINS OVER WESTERN PENNSYLVANIA
ASSOCIATED WITH THE ADVANCING COLD FRONT. THE FRONT AND ASSOCIATED
SHOWERS WILL MARCH ACROSS CENTRAL PENNSYLVANIA TODAY...REACHING
LOWER SUSQUEHANNA REGION AROUND 19Z. WHILE CIGS SHOULD REMAIN
GENERALLY IN THE VFR CATEGORY IN MOST AREAS...WILL SEE CIGS DROP
TO MVFR CONDITIONS SHORTLY IN KBFD WITH THE FRONT.
EXPECT MAINLY SHOWER ACTIVITY OVER AREAS WEST OF KUNV...WITH SOME
TSRA DEVELOPING OVER SOUTHEASTERN AREAS INCLUDING KMDT AND KLNS.
DID INCLUDE VCTS IN THE SOUTHEAST TAFS...BUT UNSURE OF JUST HOW
EXTENSIVE TSRA COVERAGE WILL BE.
COLD ADVECTION AND CYCLONIC FLOW ALOFT COUPLED WITH LOW LEVEL
MOISTURE LEFT OVER FROM TODAYS PRECIPITATION WILL LIKELY SPELL
SOME OVERNIGHT STRATUS AND FOG FRIDAY NIGHT WITH MVFR
CONDITIONS...AND SOME IFR IN THE NORTHERN AND WESTERN MOUNTAINS.
DRIER AND COOLER AIR WORKS IN FOR THE WEEKEND...AND EARLY NEXT WEEK.
OUTLOOK...
SAT-TUE...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...DEVOIR/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
747 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL TRAVERSE THE AREA TODAY ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL STALL OUT JUST
OFFSHORE NEW ENGLAND...AND EXTEND SOUTHWARD ALONG THE MID-ATLANTIC
PIEDMONT INTO SATURDAY. AN ANOMALOUS UPPER LEVEL TROUGH WILL
EVOLVE OVER THE EASTERN HALF OF THE NATION THROUGH EARLY NEXT
WEEK...RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
11Z RADAR SHOWS LINE OF SHOWERS/LEADING EDGE OF SFC COLD FRONT
MOVING INTO NW WARREN CO. INCREASED POPS ACRS THE NW MTNS TO
CATEGORICAL FM 12-15Z AS STRONG 850MB MSTR FLUX/FRONTAL
CONVERGENCE COMBINES WITH ENHANCED UVM/DIV ALOFT ASSOCD WITH THE
RIGHT ENTRANCE REGION OF 85KT UPPER JET MAX TO PRODUCE A NEARLY
SOLID LINE OF SHOWERS/TSTMS. THE COSPA/HRRR IS HANDLING THE PCPN
EVOLUTION REASONABLY WELL SO FAR THIS MORNING...AND BRINGS
CONVECTION INTO THE WESTERN ALLEGHENIES/LAUREL HIGHLANDS 15-18Z.
A CLOSED H5 LOW WILL PIVOT EWD ACRS NRN ONTARIO AND BECOME NEARLY
STATIONARY OVER JAMES BAY...WITH A BROAD LONGWAVE TROUGH AND
CYCLONIC FLOW ALOFT OVERSPREADING THE GREAT LAKES/NORTHEAST/MID-
ATLANTIC REGIONS. AT THE SFC...SHOWERS AND TSTMS WILL BE FOCUSED
ALONG/AHEAD OF THE ATTENDANT COLD FRONT THAT WILL TRAVERSE THE
AREA BY TONIGHT. HAVE MAINTAINED LKLY-CATG POPS THRU 00Z WITH
BASIN-AVG QPF AMTS AROUND 0.25 INCH.
IT STILL APPEARS THAT RESIDUAL CLOUDS/PRECIPITATION MAY BE A
LIMITING FACTOR CONCERNING SVR WX POTENTIAL THIS AFTN. IN
ADDITION...MARGINAL/MODEST INSTABILITY AXIS PRECEDING THE FRONT
DOES NOT LINE UP WITH THE STRONGEST CYCLONIC FLOW ALOFT/DEEP LAYER
SHEAR WHICH LAGS TO THE WNW. SPC HAS KEPT THE AREA IN SEE TEXT
DUE TO THE UNCERTAINTY...AND IN GENERAL FEEL THAT THE OVERALL SET-
UP DOES NOT LOOK THAT FAVORABLE FOR SVR. HOWEVER IF BETTER
INSTABILITY CAN BE REALIZED...THE CONVECTIVE ENVIRONMENT WOULD
SUPPORT SEMI-ORGANIZED STRUCTURES WITH PERHAPS A MIX OF PULSE AND
MULTICELL STORM MODES. THE BEST CHC FOR STG TO SVR STORMS IS LKLY
OVR THE ERN 1/2 OF THE CWA GIVEN LESS CLOUDS/BETTER HEATING. THE
HIGH RES NAM AND HRRR SIMULATED REFLECTIVITY SUGGEST A LINE OF
ENHANCED STORMS WILL FORM NEAR AOO-UNV-IPT LINE BY 19Z.
MUCH DRIER AIR WILL BE DIRECTED INTO THE AREA IN THE WAKE OF THE
COLD FRONT...WITH PCPN ENDING ACRS THE N/W HALF OF THE CWA BY LATE
AFTN/EARLY EVE. AS THE CLOSED LOW BECOMES NEARLY STATIONARY OVER
JAMES BAY..THE COLD FRONT WILL SLOW ITS EWD PROGRESSION AND REMAIN
A FOCUS FOR SHOWERS/ISOLD TSTMS ACRS THE SERN 1/2 OF THE CWA THRU
TNT. THE 17/00Z MDLS SHOW ONE OR MORE WAVES DEVELOPING ALONG THE
FNT AS IT SLOWS DOWN OVR ERN PA. THE NAM IS THE MOST AGGRESSIVE
WITH THIS FEATURE FOLLOWED BY THE CANADIAN. THE 00Z GFS IS MORE
PROGRESSIVE AND LOOKS SIMILAR TO THE UKMET/ECMWF. THEREFORE HAVE
INCREASED POPS INTO LKLY RANGE FOR THE FAR SE ZONES AFT 00Z.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
THE LG SCALE PATTERN WILL CONTINUE TO BE DOMINATED BY BROAD CYC
FLOW ALOFT ASSOCD WITH DEEP UPPER LEVEL TROUGH EXPANDING OVER THE
ERN CONUS...WITH HEIGHTS FCST TO REACH 3 SD BELOW NORMAL AT 500MB
OVER THE MS/OH VLYS. MUCH OF THE REGION WILL BE UNDER THE
INFLUENCE OF RELATIVELY COOL AND ABNORMALLY DRY SFC HIGH PRES
CENTERED OVR THE SRN GRT LKS/MIDWEST. THE FORECAST CHALLENGE FOR
D2 REVOLVES AROUND THE SLOWING/STALLING COLD FRONT OVR THE MID-
ATLC PIEDMONT...WHICH SHOULD SLOWLY DRIFT EWD TO THE COAST BY THE
END OF THE PD. THE NAM/GEM CONTINUE TO BE NORTH OF OTHER SOLUTIONS
AND KEEP PCPN GOING OVR SE PA INTO SAT EVE. WILL EMPLOY A MIDDLE
GROUND APPROACH AND KEEP LOW POPS GOING ACRS THE FAR SERN ZONES
THRU THE FIRST HALF OF D2. FCST TEMPS WILL AVG BELOW NORMAL ON
SAT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MDL DATA INDICATES THE DEEP UPPER LEVEL TROUGH WILL UNDERGO
ADDITIONAL AMPLIFICATION SUN-MON...AS SECONDARY S/W DROPS SWD FM
THE NRN PLAINS AND DIGS/SHARPENS THE TROUGH INTO THE LWR MS/TN
VLYS. IN RESPONSE TO HEIGHT FALLS AND ENHANCED UPPER LEVEL
DIVERGENCE VIA STRENGTHENING RT ENTRANCE REGION JET DYNAMICS...THE
ECMWF/CANADIAN FORM A LOW OVR THE SRN MID-ATLC COAST BY 12Z MON.
THE GFS HINTS AT THIS IDEA BUT IS NOT AS WELL-DEVELOPED WITH ITS
SFC LOW. CONSENSUS BLEND SUPPORTS LOW-END CHC POPS MAINLY FM SUN
NGT INTO THE DAY ON MONDAY.
THE HIGH-AMPLITUDE UPPER TROUGH EAST OF THE MS RIVER WILL REMAIN
Q-STNRY AND SLOWLY DEAMPLIFY INTO THE SECOND HALF OF THE PD TUE-
THURS. THIS PD SHOULD FEATURE MAINLY FAIR/DRY WEATHER WITH SFC
HIGH PRES IN CONTROL. RISING HEIGHTS AND GRADUAL RETURN FLOW WILL
LKLY ALLOW FOR A MODERATION IN TEMPS BACK TO AT LEAST SEASONAL
NORMALS...IF NOT ABOVE NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
BAND OF SCATTERED SHOWERS STILL REMAINS OVER WESTERN PENNSYLVANIA
ASSOCIATED WITH THE ADVANCING COLD FRONT. THE FRONT AND ASSOCIATED
SHOWERS WILL MARCH ACROSS CENTRAL PENNSYLVANIA TODAY...REACHING
LOWER SUSQUEHANNA REGION AROUND 19Z. WHILE CIGS SHOULD REMAIN
GENERALLY IN THE VFR CATEGORY IN MOST AREAS...WILL SEE CIGS DROP
TO MVFR CONDITIONS SHORTLY IN KBFD WITH THE FRONT.
EXPECT MAINLY SHOWER ACTIVITY OVER AREAS WEST OF KUNV...WITH SOME
TSRA DEVELOPING OVER SOUTHEASTERN AREAS INCLUDING KMDT AND KLNS.
DID INCLUDE VCTS IN THE SOUTHEAST TAFS...BUT UNSURE OF JUST HOW
EXTENSIVE TSRA COVERAGE WILL BE.
COLD ADVECTION AND CYCLONIC FLOW ALOFT COUPLED WITH LOW LEVEL
MOISTURE LEFT OVER FROM TODAYS PRECIPITATION WILL LIKELY SPELL
SOME OVERNIGHT STRATUS AND FOG FRIDAY NIGHT WITH MVFR
CONDITIONS...AND SOME IFR IN THE NORTHERN AND WESTERN MOUNTAINS.
DRIER AND COOLER AIR WORKS IN FOR THE WEEKEND...AND EARLY NEXT WEEK.
OUTLOOK...
SAT-TUE...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
659 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL TRAVERSE THE AREA TODAY ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE COLD FRONT WILL STALL OUT JUST
OFFSHORE NEW ENGLAND...AND EXTEND SOUTHWARD ALONG THE MID-ATLANTIC
PIEDMONT INTO SATURDAY. AN ANOMALOUS UPPER LEVEL TROUGH WILL
EVOLVE OVER THE EASTERN HALF OF THE NATION THROUGH EARLY NEXT
WEEK...RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
11Z RADAR SHOWS LINE OF SHOWERS/LEADING EDGE OF SFC COLD FRONT
MOVING INTO NW WARREN CO. INCREASED POPS ACRS THE NW MTNS TO
CATEGORICAL FM 12-15Z AS STRONG 850MB MSTR FLUX/FRONTAL
CONVERGENCE COMBINES WITH ENHANCED UVM/DIV ALOFT ASSOCD WITH THE
RIGHT ENTRANCE REGION OF 85KT UPPER JET MAX TO PRODUCE A NEARLY
SOLID LINE OF SHOWERS/TSTMS. THE COSPA/HRRR IS HANDLING THE PCPN
EVOLUTION REASONABLY WELL SO FAR THIS MORNING...AND BRINGS
CONVECTION INTO THE WESTERN ALLEGHENIES/LAUREL HIGHLANDS 15-18Z.
A CLOSED H5 LOW WILL PIVOT EWD ACRS NRN ONTARIO AND BECOME NEARLY
STATIONARY OVER JAMES BAY...WITH A BROAD LONGWAVE TROUGH AND
CYCLONIC FLOW ALOFT OVERSPREADING THE GREAT LAKES/NORTHEAST/MID-
ATLANTIC REGIONS. AT THE SFC...SHOWERS AND TSTMS WILL BE FOCUSED
ALONG/AHEAD OF THE ATTENDANT COLD FRONT THAT WILL TRAVERSE THE
AREA BY TONIGHT. HAVE MAINTAINED LKLY-CATG POPS THRU 00Z WITH
BASIN-AVG QPF AMTS AROUND 0.25 INCH.
IT STILL APPEARS THAT RESIDUAL CLOUDS/PRECIPITATION MAY BE A
LIMITING FACTOR CONCERNING SVR WX POTENTIAL THIS AFTN. IN
ADDITION...MARGINAL/MODEST INSTABILITY AXIS PRECEDING THE FRONT
DOES NOT LINE UP WITH THE STRONGEST CYCLONIC FLOW ALOFT/DEEP LAYER
SHEAR WHICH LAGS TO THE WNW. SPC HAS KEPT THE AREA IN SEE TEXT
DUE TO THE UNCERTAINTY...AND IN GENERAL FEEL THAT THE OVERALL SET-
UP DOES NOT LOOK THAT FAVORABLE FOR SVR. HOWEVER IF BETTER
INSTABILITY CAN BE REALIZED...THE CONVECTIVE ENVIRONMENT WOULD
SUPPORT SEMI-ORGANIZED STRUCTURES WITH PERHAPS A MIX OF PULSE AND
MULTICELL STORM MODES. THE BEST CHC FOR STG TO SVR STORMS IS LKLY
OVR THE ERN 1/2 OF THE CWA GIVEN LESS CLOUDS/BETTER HEATING. THE
HIGH RES NAM AND HRRR SIMULATED REFLECTIVITY SUGGEST A LINE OF
ENHANCED STORMS WILL FORM NEAR AOO-UNV-IPT LINE BY 19Z.
MUCH DRIER AIR WILL BE DIRECTED INTO THE AREA IN THE WAKE OF THE
COLD FRONT...WITH PCPN ENDING ACRS THE N/W HALF OF THE CWA BY LATE
AFTN/EARLY EVE. AS THE CLOSED LOW BECOMES NEARLY STATIONARY OVER
JAMES BAY..THE COLD FRONT WILL SLOW ITS EWD PROGRESSION AND REMAIN
A FOCUS FOR SHOWERS/ISOLD TSTMS ACRS THE SERN 1/2 OF THE CWA THRU
TNT. THE 17/00Z MDLS SHOW ONE OR MORE WAVES DEVELOPING ALONG THE
FNT AS IT SLOWS DOWN OVR ERN PA. THE NAM IS THE MOST AGGRESSIVE
WITH THIS FEATURE FOLLOWED BY THE CANADIAN. THE 00Z GFS IS MORE
PROGRESSIVE AND LOOKS SIMILAR TO THE UKMET/ECMWF. THEREFORE HAVE
INCREASED POPS INTO LKLY RANGE FOR THE FAR SE ZONES AFT 00Z.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
THE LG SCALE PATTERN WILL CONTINUE TO BE DOMINATED BY BROAD CYC
FLOW ALOFT ASSOCD WITH DEEP UPPER LEVEL TROUGH EXPANDING OVER THE
ERN CONUS...WITH HEIGHTS FCST TO REACH 3 SD BELOW NORMAL AT 500MB
OVER THE MS/OH VLYS. MUCH OF THE REGION WILL BE UNDER THE
INFLUENCE OF RELATIVELY COOL AND ABNORMALLY DRY SFC HIGH PRES
CENTERED OVR THE SRN GRT LKS/MIDWEST. THE FORECAST CHALLENGE FOR
D2 REVOLVES AROUND THE SLOWING/STALLING COLD FRONT OVR THE MID-
ATLC PIEDMONT...WHICH SHOULD SLOWLY DRIFT EWD TO THE COAST BY THE
END OF THE PD. THE NAM/GEM CONTINUE TO BE NORTH OF OTHER SOLUTIONS
AND KEEP PCPN GOING OVR SE PA INTO SAT EVE. WILL EMPLOY A MIDDLE
GROUND APPROACH AND KEEP LOW POPS GOING ACRS THE FAR SERN ZONES
THRU THE FIRST HALF OF D2. FCST TEMPS WILL AVG BELOW NORMAL ON
SAT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MDL DATA INDICATES THE DEEP UPPER LEVEL TROUGH WILL UNDERGO
ADDITIONAL AMPLIFICATION SUN-MON...AS SECONDARY S/W DROPS SWD FM
THE NRN PLAINS AND DIGS/SHARPENS THE TROUGH INTO THE LWR MS/TN
VLYS. IN RESPONSE TO HEIGHT FALLS AND ENHANCED UPPER LEVEL
DIVERGENCE VIA STRENGTHENING RT ENTRANCE REGION JET DYNAMICS...THE
ECMWF/CANADIAN FORM A LOW OVR THE SRN MID-ATLC COAST BY 12Z MON.
THE GFS HINTS AT THIS IDEA BUT IS NOT AS WELL-DEVELOPED WITH ITS
SFC LOW. CONSENSUS BLEND SUPPORTS LOW-END CHC POPS MAINLY FM SUN
NGT INTO THE DAY ON MONDAY.
THE HIGH-AMPLITUDE UPPER TROUGH EAST OF THE MS RIVER WILL REMAIN
Q-STNRY AND SLOWLY DEAMPLIFY INTO THE SECOND HALF OF THE PD TUE-
THURS. THIS PD SHOULD FEATURE MAINLY FAIR/DRY WEATHER WITH SFC
HIGH PRES IN CONTROL. RISING HEIGHTS AND GRADUAL RETURN FLOW WILL
LKLY ALLOW FOR A MODERATION IN TEMPS BACK TO AT LEAST SEASONAL
NORMALS...IF NOT ABOVE NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
ADVANCING BAND OF SHOWERS NOW ENCROACHING FROM THE WEST...WITH THE
LEADING EDGE OF THE ACTIVITY JUST THROUGH KERI AT 09Z. OVERALL...VFR
CONDITIONS CONTINUE ACROSS MOST OF CENTRAL PA ATTM. THE EXCEPTION
IS ACROSS THE MIDDLE AND LOWER SUSQUEHANNA VALLEY WHERE MVFR TO
LOCALLY IFR CONDITIONS NOW EXIST IN FOG. EXPECT THIS TO CONTINUE
THROUGH 14Z-15Z AS THICKENING CLOUDS MAY RETARD FOG DISSIPATION.
APPROACHING FRONT WILL SWEEP A CORRIDOR OF PRECIPITATION ACROSS
REGION TODAY. SHOWERS WILL AFFECT KBFD FIRST...AROUND 11Z. EXPECT
CIGS HERE TO QUICKLY DROP TO MVFR LEVELS AS PRECIPITATION BEGINS.
PRECIPITATION WILL ACROSS CENTRAL SECTIONS BY LATE MORNING...AND
FINALLY INTO SOUTHEAST AREAS BY LATER IN THE AFTERNOON. IN
ADDITION THERE WILL BE SOME TSRA DEVELOPING IN THE SHRA ACTIVITY.
AS FOR PRECIPITATION COVERAGE...MOST EXTENSIVE WILL LIKELY BE IN
THE MORNING HOURS IN THE WEST...WITH ACTIVITY BECOMING MORE
CELLULAR AND CONVECTIVE IN NATURE DURING THE AFTERNOON. FOR THIS
REASON MENTIONED CATEGORICAL SHRA IN KBFD AND KJST...WITH JUST
VCSH IN OTHER TAFS.
QUESTION ALSO IS EXTENT OF TSRA ACTIVITY. ATTM...KEPT VCTS OUT OF
TAFS...WITH THE IDEA THAT IF MORE ORGANIZED ACTIVITY DEVELOPS LATER
TODAY WILL INCLUDE IN SUBSEQUENT ISSUANCES. ALTHOUGH NOT MENTIONED
IN TAFS ATTM...AVIATION INTERESTS SHOULD EXPECT AT LEAST SCATTERED
TSRA DURING THE AFTERNOON OVER CENTRAL AND EASTERN AREAS OF CENTRAL
PA.
COLD ADVECTION AND CYCLONIC FLOW ALOFT COUPLED WITH LOW LEVEL
MOISTURE LEFT OVER FROM TODAYS PRECIPITATION WILL LIKELY SPELL SOME
OVERNIGHT STRATUS AND FOG FRIDAY NIGHT WITH MVFR CONDITIONS...AND
SOME IFR IN THE NORTHERN AND WESTERN MOUNTAINS.
DRIER AND COOLER AIR WORKS IN FOR THE WEEKEND...AND EARLY NEXT WEEK.
OUTLOOK...
SAT-TUE...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1019 AM CDT FRI AUG 17 2012
.UPDATE...
AS OF 10 AM...SKIES ACROSS THE MIDSOUTH WERE MOSTLY CLOUDY. AN
AREA OF SHOWERS AND A FEW THUNDERSTORMS WAS MOVING ACROSS
NORTHEASTERN ARKANSAS INTO WEST TENNESSEE AND NORTHWEST
MISSISSIPPI. THESE SHOWERS AND STORMS HAVE DEVELOPED AHEAD OF A
SHORTWAVE THAT WAS VISIBLE ON RADAR. IT IS INTERESTING TO NOTE THE
LACK OF ACTIVITY BEHIND THE SHORTWAVE. TEMPERATURES ACROSS THE
REGION RANGED FROM THE LOWER TO UPPER 70S.
WITH THE SHOWERS AND THUNDERSTORMS THAT OCCURRED LAST NIGHT AND
THE ACTIVITY MOVING THROUGH NOW...THE SEVERE WEATHER CHANCES
WOULD SEEM TO BE LOWER FOR THIS AFTERNOON. HOWEVER...THERE ARE
BREAKS IN THE CLOUDS ACROSS CENTRAL ARKANSAS AND CENTRAL
MISSISSIPPI AND TEMPERATURES HAVE JUMPED INTO THE UPPER 70S TO
LOW 80S. IF THE CLOUDS BEGIN TO BREAK UP ACROSS THE MIDSOUTH...
THEN TEMPERATURES WILL GO UP AND SO WILL THE INSTABILITY FOR
POTENTIAL STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON. THE
LATEST NAM GUIDANCE SUGGESTS THESE SHOWERS AND THUNDERSTORMS
CURRENTLY IN NORTHEAST ARKANSAS WILL CONTINUE MOVING ACROSS THE
MIDSOUTH. THE LATEST NAM ALSO SUGGESTS STORMS RE-FIRING ALONG THE
COLD FRONT IN WEST TENNESSEE AND NORTHEAST ARKANSAS THIS MORNING.
IT IS SOMEWHAT HARD TO BELIEVE THIS SCENARIO AT THIS POINT WITH
THE DENSE OVERCAST ACROSS THE REGION. FOR THE TIME BEING...THE
FORECAST HAS BEEN LEFT UNTOUCHED. THE POTENTIAL FOR STRONG TO
SEVERE STORMS THIS AFTERNOON ACROSS NORTH MISSISSIPPI IS HEAVILY
DEPENDENT ON THE CLOUD COVER AND STABILITY OF THE ATMOSPHERE IN
THE WAKE OF PREVIOUS AND ONGOING CONVECTION.
RRH
&&
.PREV DISCUSSION... /ISSUED 621 AM CDT FRI AUG 17 2012/
DISCUSSION... /ISSUED 505 AM CDT FRI AUG 17 2012/
LINEAR THUNDERSTORM COMPLEX THAT DROPPED THROUGH THE MIDSOUTH
EARLY THIS MORNING WAS MOVING INTO CENTRAL MS AND WEST CENTRAL AL
AT DISCUSSION TIME. THIS STORM COMPLEX OCCURRED AHEAD OF A HEIGHT
FALLS SPREADING INTO THE MID MS RIVER VALLEY... AND HAD PROPAGATED
SOUTHWARD INTO MODERATE INSTABILITY OVER THE MIDSOUTH ONCE IT HAD
AN ESTABLISHED COLD POOL.
ADDITIONAL SHOWERS AND THUNDERSTORMS OVER NORTHEAST AR HAVE FORMED
EARLY THIS MORNING...IN ADVANCE OF A WELL DEFINED MIDLEVEL
SHORTWAVE MOVING INTO WESTERN AR. ONCE THIS FEATURE PUSHES EAST...
NVA BEHIND THE SHORTWAVE AND THE INTRUSION OF DRIER AND MORE
STABLE LOW LEVEL AIR SHOULD LIMIT IF NOT END RAIN CHANCES NORTH
OF I40 THROUGH THE AFTERNOON. THE SURFACE COLD FRONT WILL PUSH
INTO CENTRAL MS BY MIDEVENING...WITH RAIN CHANCES TAPERING OFF
OVER NORTH MS.
AFTERNOON TEMPERATURES 5 TO 7 DEGREES BELOW MID/LATE AUGUST
NORMALS WILL PREVAIL INTO THE EARLY PART OF THE UPCOMING WORKWEEK. FEW
CHANGES HAVE BEEN MADE TO EARLIER FORECASTS... BUT HAVE INTRODUCED
LOW END RAIN CHANCES FOR SUNDAY...MAINLY SOUTH AND WEST OF
MEMPHIS. NAM/GFS/ECMWF MODELS SHOW A NORTHWEST FLOW SHORTWAVE
DROPPING INTO THE ARKLAMISS REGION...WHERE PRECIPITABLE WATER
VALUES OF 2 INCHES WILL BE COMMON. LESS AVAILABLE MOISTURE WILL
BE AVAILABLE OVER THE MIDSOUTH. PRIMARY IMPACT MAY JUST BE
INCREASED MIDLEVEL CLOUDINESS IN MOST AREAS.
LOOKING TO THE OUTER PERIODS... GFS...CMC AND ECMWF MODELS SHOW
NORTHWEST FLOW REPLACED BY A BROAD UPPER LEVEL HEIGHT RIDGE OVER
THE SOUTHERN U.S.. ECMWF DEVELOPS A WEAK CUTOFF LOW OVER THE
LOWER/MID MS RIVER VALLEY IN THE MID TO LATE WEEK... BUT THIS IS
NOT CORROBORATED BY THE GFS OR CMC MODELS. HAVE KEPT THE EXTENDED
PERIODS MAINLY DRY...WITH NEAR TO SLIGHTLY ABOVE NORMAL TEMPS.
PWB
AVIATION...
12Z TAF SET
NEXT ROUND OF SHOWERS AND THUNDERSTORMS BEGINNING TO PUSH INTO
EASTERN ARKANSAS AT THIS TIME. HAVE THROWN IN A TEMPO AT KJBR THROUGH
14Z FOR LOWER VSBYS AND CIGS AND TO MENTION TSRA. HAVE ALSO
INTRODUCED A TEMPO AT KMEM THROUGH 15Z BUT WILL ONLY MENTION SHRA
AS LINE SHOULD WEAKEN AS IT PUSHES SOUTHEAST. EXPECT AREA TO
DISSIPATE OVER NORTHWEST MISSISSIPPI AROUND 15Z. LATEST HRRR MODEL
INDICATES REDEVELOPMENT WILL OCCUR ALONG OLD OUTFLOW BOUNDARIES
SOUTH AND SOUTHWEST OF KMEM. HAVE MENTION OF VCTS AT KMEM
BEGINNING AT 19Z WHILE MENTION OF KTUP BEGINS AT 20Z. BY
00-01Z...EXPECT SHRA/TSRA ACTIVITY TO BEGIN DISSIPATING.
OTHERWISE...VFR CONDITIONS EXPECTED. NORTHERLY WINDS AROUND 5-10
KTS EXPECTED TODAY.
KRM
&&
.AVIATION...
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 86 64 83 65 / 50 10 10 10
MKL 83 59 81 57 / 50 10 10 10
JBR 81 61 81 62 / 40 10 10 20
TUP 86 66 85 65 / 80 30 10 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
621 AM CDT FRI AUG 17 2012
.DISCUSSION... /ISSUED 505 AM CDT FRI AUG 17 2012/
LINEAR THUNDERSTORM COMPLEX THAT DROPPED THROUGH THE MIDSOUTH
EARLY THIS MORNING WAS MOVING INTO CENTRAL MS AND WEST CENTRAL AL
AT DISCUSSION TIME. THIS STORM COMPLEX OCCURRED AHEAD OF A HEIGHT
FALLS SPREADING INTO THE MID MS RIVER VALLEY... AND HAD PROPAGATED
SOUTHWARD INTO MODERATE INSTABILITY OVER THE MIDSOUTH ONCE IT HAD
AN ESTABLISHED COLD POOL.
ADDITIONAL SHOWERS AND THUNDERSTORMS OVER NORTHEAST AR HAVE FORMED
EARLY THIS MORNING...IN ADVANCE OF A WELL DEFINED MIDLEVEL
SHORTWAVE MOVING INTO WESTERN AR. ONCE THIS FEATURE PUSHES EAST...
NVA BEHIND THE SHORTWAVE AND THE INTRUSION OF DRIER AND MORE
STABLE LOW LEVEL AIR SHOULD LIMIT IF NOT END RAIN CHANCES NORTH
OF I40 THROUGH THE AFTERNOON. THE SURFACE COLD FRONT WILL PUSH
INTO CENTRAL MS BY MIDEVENING...WITH RAIN CHANCES TAPERING OFF
OVER NORTH MS.
AFTERNOON TEMPERATURES 5 TO 7 DEGREES BELOW MID/LATE AUGUST
NORMALS WILL PREVAIL INTO THE EARLY PART OF THE UPCOMING WORKWEEK. FEW
CHANGES HAVE BEEN MADE TO EARLIER FORECASTS... BUT HAVE INTRODUCED
LOW END RAIN CHANCES FOR SUNDAY...MAINLY SOUTH AND WEST OF
MEMPHIS. NAM/GFS/ECMWF MODELS SHOW A NORTHWEST FLOW SHORTWAVE
DROPPING INTO THE ARKLAMISS REGION...WHERE PRECIPITABLE WATER
VALUES OF 2 INCHES WILL BE COMMON. LESS AVAILABLE MOISTURE WILL
BE AVAILABLE OVER THE MIDSOUTH. PRIMARY IMPACT MAY JUST BE
INCREASED MIDLEVEL CLOUDINESS IN MOST AREAS.
LOOKING TO THE OUTER PERIODS... GFS...CMC AND ECMWF MODELS SHOW
NORTHWEST FLOW REPLACED BY A BROAD UPPER LEVEL HEIGHT RIDGE OVER
THE SOUTHERN U.S.. ECMWF DEVELOPS A WEAK CUTOFF LOW OVER THE
LOWER/MID MS RIVER VALLEY IN THE MID TO LATE WEEK... BUT THIS IS
NOT CORROBORATED BY THE GFS OR CMC MODELS. HAVE KEPT THE EXTENDED
PERIODS MAINLY DRY...WITH NEAR TO SLIGHTLY ABOVE NORMAL TEMPS.
PWB
&&
.AVIATION...
12Z TAF SET
NEXT ROUND OF SHOWERS AND THUNDERSTORMS BEGINNING TO PUSH INTO
EASTERN ARKANSAS AT THIS TIME. HAVE THROWN IN A TEMPO AT KJBR THROUGH
14Z FOR LOWER VSBYS AND CIGS AND TO MENTION TSRA. HAVE ALSO
INTRODUCED A TEMPO AT KMEM THROUGH 15Z BUT WILL ONLY MENTION SHRA
AS LINE SHOULD WEAKEN AS IT PUSHES SOUTHEAST. EXPECT AREA TO
DISSIPATE OVER NORTHWEST MISSISSIPPI AROUND 15Z. LATEST HRRR MODEL
INDICATES REDEVELOPMENT WILL OCCUR ALONG OLD OUTFLOW BOUNDARIES
SOUTH AND SOUTHWEST OF KMEM. HAVE MENTION OF VCTS AT KMEM
BEGINNING AT 19Z WHILE MENTION OF KTUP BEGINS AT 20Z. BY
00-01Z...EXPECT SHRA/TSRA ACTIVITY TO BEGIN DISSIPATING.
OTHERWISE...VFR CONDITIONS EXPECTED. NORTHERLY WINDS ARPUND 5-10
KTS EXPECTED TODAY.
KRM
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 86 64 83 65 / 70 10 10 10
MKL 83 59 81 57 / 50 10 10 10
JBR 81 61 81 62 / 40 10 10 20
TUP 86 66 85 65 / 90 30 10 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1252 AM CDT FRI AUG 17 2012
.MESOSCALE UPDATE...
LINE OF STRONG/SEVERE STORMS NOW NEARING ALABAMA BORDER WHILE
CONTINUING TO SINK SOUTH...WITH RAIN SHIELD EXTENDING ALL THE WAY
TO THE KENTUCKY BORDER. FLASH DENSITY/LMA REMAINS QUITE HIGH BUT
MOSTLY NEGATIVE STRIKES NEAR ALABAMA BORDER. RUC SHOWING GOOD
UPPER DIFFLUENCE OVER SOUTHERN MIDDLE TENNESSEE AT 05Z.
EXPECT LINE TO CONTINUE SOUTH BOUND AND SHOULD EXIT MID STATE
AROUND 0630Z BUT RAIN SHIELD WILL REMAIN OVER REMAINDER OF THE MID
STATE FOR THE NEXT SEVERAL HOURS.
MSAS HAS COLD FRONT EXTENDING FROM SOUTHWEST INDIANA DOWN THROUGH
FAR SOUTHERN ILLINOIS INTO SOUTHEAST MISSOURI. TROPOSPHERE HAS
BEEN WORKED OVER FROM TONIGHTS CONVECTION. MODELS DROP FRONT
SOUTHEAST AND INTO THE MID STATE DURING THE DAY TODAY WITH MORE
SHOWERS AND STORMS. STORMS HAVE ALREADY RE-FIRED IN SOUTHWEST MISSOURI.
BOYD
&&
.PREV DISCUSSION... /ISSUED 943 PM CDT THU AUG 16 2012/
MESOSCALE UPDATE...STORMS MOVING INTO NW AND NC MID TN WITH
PRETTY GOOD PUSH OF WIND. PER DISCUSSION WITH SPC...NOT PLANNING A
WATCH AT THIS TIME...ALTHOUGH WE WILL HAVE SOME SEVERE WIND
POTENTIAL FOR ANOTHER HOUR OR 2. HOPEFULLY AS SPC DISCUSSION
INDICATES...THE STORM SUPPORT WILL DIMINISH AS THE OUTFLOW PUSHES
SOUTHWARD. FOLKS IN THE NASHVILLE METRO AREA SHOULD EXPECT SOME
GUSTY WINDS SOON.
13
PREV DISCUSSION... /ISSUED 758 PM CDT THU AUG 16 2012/
MESOSCALE UPDATE...WE ARE CLOSELY MONITORING STORMS OVER WEST KY
WITH HIGH WINDS TO 70 MPH REPORTED IN THE PAH AREA. GUST FRONT
WILL PUSH TO OUR NW COUNTIES BY 0130Z. IN ADDITION TO THESE
STORMS...SEVERAL SINGLE CELL PULSE STORMS HAVE POPPED UP OVER MID
TN THIS EVENING...WITH 1 INCH DIAMETER HAIL REPORTED IN SOUTH
RUTHERFORD COUNTY.
THE EVENING OHX SOUNDING SHOWED 1228 CAPE AND -5 LIFTED INDEX.
CONDITIONS SHOULD STABILIZE SOME WITH SUNSET...SO THE PULSE
ACTIVITY SHOULD TREND DOWNWARD IN INTENSITY. MAIN CONCERN WILL BE
STRONG GUSTY WINDS OVER THE NW COUNTIES THROUGH THE NEXT FEW
HOURS. ALSO...SOME VERY HEAVY DOWNPOURS MAY CAUSE SOME STREET
FLOODING.
FORECAST PRODUCTS HAVE ALREADY BEEN UPDATED TO INCREASE POPS NW.
13
PREV DISCUSSION... /ISSUED 249 PM CDT THU AUG 16 2012/
DISCUSSION...FRONT IS TO THE NW OVER CNTRL MO MOVING SEWD WHILE
AN OLD DISSIPATING FRONT IS TO THE SOUTH OVER GA/AL/MS. THUS THESE
2 FEATURES SERVE TO FOCUS CONVECTION OVER THE OH VALLEY AND DEEP
SOUTH. NO SIGNIFICANT CONVECTION PRESENTLY OVER THE MIDSTATE.
MAINILY DUE TO THE MID LEVEL INVERSION AND LACK OF DEEP MOISTURE.
AS THE FRONTAL ZONE MOVES CLOSER LATE TODAY WE MAY START TO PICK
SOME CONVECTION IN THE EXTREME NW COUNTIES. THAT ACTIVITY WILL
SPREAD EWD ACROSS THE AREA BUT WILL THIN A GOOD BIT IN THE EAST
WHERE MOISTURE IS NOT AS PLENTIFUL. THE FRONT(WIND SHIFT) IS
EXPECTED TO ARRIVE IN THE NWRN COUNTIES BETWEEN 08Z AND 09Z WITH
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORM ALONG AND AHEAD OF
THE FRONT. IT SHOULD BE EAST OF KBNA BY 17Z AND AT KCSV 19Z TO
20Z.
SHOWERS AND THUNDERSTORMS WILL DIMINISH FROM THE WEST FRIDAY NIGHT
AS DRIER AIR PUSHES INTO THE MIDSTATE. HOWEVER, THE FRONT DOES NOT
PUSH FAR ENOUGH SOUTH TO TOTALLY PUSH ALL OF THE PRECIP OUT OF THE
AREA. I`VE LEFT A SLIVER OF POPS OVER THE SRN MOST AND SERN MOST
COUNTIES FOR SAT AND SUN.
THEN A 2ND SURGE OF DRY AIR PUSHES IN SUN NGT AND MON MOVING THE
FRONT AND ITS MOISTURE FURTHER INTO THE DEEP SOUTH. THINK THE GFS
IS A BIT TOO FAST IN BRINGING BACK MOISTURE IN THE WEST AND HAVE
KEPT THE AREA DRY THROUGH WED NGT. ANOTHER FRONTAL SYSTEM
APPROACHES ON THU SO I`VE INCLUDED A 20 POP FOR THU AND THU NGT.
SEVERE...SPC HAS OUTLOOKED A SLGT CHC AREA OVER THE WRN OH VALLEY.
ANY SVR CONVECTION THAT FORMS IN THIS AREA WILL LIKELY DROP BELOW
SVR LIMITS AS THE FRONT MOVES INTO THE NW COUNTIES AFTER MIDNIGHT.
THEN WITH THE FRONT OVER THE ERN PORTION OF THE MIDSTATE TOMORROW
AFTN WHEN THE DIURNAL CYCLE RAMPS UP AGAIN THEY HAVE OUTLOOKED
AN AREA OVER THE SERN HALF OF MIDDLE TENNESSEE PLUS NRN MS/AL/GA.
BIGGEST THREAT WOULD BE DAMAGING WINDS.
HEAVY RAIN...HPC IS OUTLOOKING LESS THAN AN INCH OF RAIN FOR THIS EVENT.
WHILE THERE WILL BE SIGNIFICANT MOISTURE AHEAD OF THE FRONT...THE
FRONT IS EXPECTED TO MOVE AT A MODEST PACE ACROSS THE AREA W/O
GETTING "HUNG UP". ALSO...MUCH OF THE UPPER SUPPORT IS WELL NORTH
OF THE AREA.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
1039 PM CDT SAT AUG 18 2012
.UPDATE...
WE/VE TRIMMED POPS BACK FOR THE REMAINDER OF THE NIGHT. ASIDE FROM
THE PERSISTENT SEVERE STORM NOW MOVING ACROSS COCHRAN
COUNTY...ONLY A FEW ISOLD SHOWERS WERE PRESENT ACROSS THE FA. THERE
IS STILL SOME WEAK MID-LVL ENERGY IN THE NW FLOW ALOFT
MAINTAINING SOME SHOWERS IN NE NEW MEXICO...AND THIS ACTIVITY MAY
MAKE IT INTO OUR NW ZONES AFTER MIDNIGHT. OTHERWISE...WEAK ISENTROPIC
LIFT OF THE RELATIVELY MOIST AIRMASS WILL KEEP AN ISOLD
SHOWER/WEAK TSTM POTENTIAL GOING OVERNIGHT ACROSS THE ENTIRE AREA.
&&
.PREV DISCUSSION... /ISSUED 638 PM CDT SAT AUG 18 2012/
AVIATION...
VFR CONDITIONS EXPECTED FOR KCDS.
FOR KLBB...AN OUTFLOW BOUNDARY TO THE EAST OF KLBB SHOULD MOVE WEST
ACROSS THE TERMINAL IN THE 00Z TO 02Z TIME FRAME WITH TCU AND
POSSIBLY -TSRA IN THE VICINITY OF KLBB. ADDITIONALLY...THERE IS
A LOW PROBABILITY THAT TSRA ACTIVITY CURRENTLY IN THE TX PANHANDLE
COULD MOVE SOUTH AND IMPACT KLBB SOMEWHERE IN THE 03Z TO 09Z TIME
FRAME. OTHERWISE...SURFACE WINDS WILL TEND MORE TO THE NORTHEAST
AND NORTH AS OUTFLOW BOUNDARIES AND A WEAK COLD FRONT MOVE ACROSS
EARLY SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 551 PM CDT SAT AUG 18 2012/
UPDATE...
QUICK UPDATE TO REMOVE HALL...CHILDRESS AND COTTLE COUNTIES FROM
THE SEVERE THUNDERSTORM WATCH. OVERALL...STORM INTENSITY HAS BEEN
RATHER TAME...THOUGH A FEW CELLS DO OCCASIONALLY PULSE UP. IN
ADDITION...A SMALL CLUSTER OF STORMS COULD GENERATE GUSTY WINDS AS
THEY MOVE THROUGH THE SOUTHEASTERN ZONES OVER THE NEXT HALF HOUR
TO HOUR. UPDATED PRODUCTS HAVE BEEN SENT.
PREV DISCUSSION... /ISSUED 339 PM CDT SAT AUG 18 2012/
SHORT TERM...
WELL-DEFINED OUTFLOW BOUNDARY/COMPOSITE COLD FRONT WAS MOVING
SOUTHWEST INTO CHILDRESS AND HALL COUNTIES JUST NORTH OF A SURFACE
TROUGH STRETCHING FROM NEAR DIMMITT ESE TO SWEARINGEN. THE TRUE COLD
FRONT OF INTEREST THAT IS PROGGED TO DROP HIGHS BELOW NORMAL ON
SUNDAY /UNDER MOSTLY SUNNY SKIES!/ WAS FOUND DIVING SOUTH ACROSS WRN
KANSAS AND ERN COLORADO. BRUNT OF THE PRECIP POTENTIAL WILL BE
RELEGATED TO THE PRE-FRONTAL BOUNDARIES CURRENTLY CONVECTING ACROSS
THE NRN HALF OF THE CWA. ALTHOUGH WIND SHEAR IS WEAK THUS FAR...THIS
WILL IMPROVE AS THE AFTERNOON AND EARLY EVENING WEAR ON COURTESY OF
A SHORTWAVE TROUGH AND ASSOCIATED WIND MAX APPROACHING IN NORTHWEST
FLOW. EVEN WITH MLCAPES GENERALLY AOB 1000 J/KG...THIS IMPROVING
LIFT SHOULD SECURE A WINDOW FOR ORGANIZED SEVERE STORMS MAINLY IN
THE FORM OF SMALL SEGMENTS OR LINES WITH DMGG WINDS THE GREATEST
THREAT BEFORE INTENSITY AND STORM COVERAGE WANE BY LATE EVENING.
CURRENT SVR WATCH CAPTURES THIS THREAT WELL...BUT MAY REQUIRE
EXPANSION SWWD SHOULD TRENDS WARRANT. A FEW HI-RES MODELS SUCH AS
THE TTU WRF AND HRRR DO INDICATE SUCH A SCENARIO FOR LUBBOCK AND
POINTS SOUTHWEST...SO THIS WILL BE MONITORED CLOSELY BY THE ONCOMING
SHIFT. OTHERWISE...FROPA WILL OCCUR AFTER MIDNIGHT FOLLOWED BY
DIMINISHING POPS. MOIST POST-FRONTAL UPSLOPE TOMORROW AFTN IN ERN NM
AND ADJACENT COUNTIES OF THE TX SOUTH PLAINS STILL APPEARS
REASONABLE FOR SLIGHT CHANCE POPS IN OUR SWRN COUNTIES...HOWEVER THE
NAM LOOKS MUCH TOO BULLISH WITH QPF IN SUCH A REGIME AND IS LARGELY
BEING DISMISSED
LONG TERM...
NNW FLOW ALOFT IS EXPECTED ON MONDAY. HIGH AMPLITUDE RIDGE WILL
SPAN FROM NWRN MEXICO UP TO NORTHERN ALBERTA. OUT EAST...MATURE LOW
WILL BE SITUATED OVER THE SRN PART OF HUDSON BAY WITH AN EMBEDDED
SHORTWAVE DUE INTO THE CENTRAL PLAINS EARLY ON TUESDAY ALTHOUGH THE
BEST ENERGY ASSOCIATED WITH THIS SYSTEM WILL LIKELY REMAIN NORTHEAST
OF THE REGION. BY MID WEEK...THE RIDGE WILL BEGIN TO MOVE EASTWARD
AND FLATTEN WITH SOME HINTS IN BOTH THE GFS AND ECM ABOUT A BIT OF A
DISTURBANCE PASSING TO OUR NORTH ON THURSDAY. WHILE THE ECM
SOLUTION WOULD BE MORE FAVORABLE INTO BRINGING A FRONT INTO THE
REGION...AND PRECIPITATION...THE GFS HAS MORE CLOSELY PARALLELED
REALITY FOR THE PAST WEEK AND THUS WILL TREND THE FORECAST IN THAT
DIRECTION.
GIVEN NWP PERFORMANCE AS OF LATE WRT QPF AM NOT COMPLETELY CONVINCED
THAT WE WILL SEE AS MUCH RAIN ACROSS THE REGION AS PREVIOUSLY
THOUGHT...BUT HAVE ELECTED ONLY TO MAKE A DOWNWARD TREND OF MONDAY
NIGHT POPS. LIKE TODAY...VIRTUALLY EVERY MODEL CONVECTS BUT PRECIP
HAS BEEN HARD TO COME BY. AS PREVIOUSLY MENTIONED...SHORTWAVE
PASSES TO OUR NORTH SOMETIME ON THURSDAY BUT AGAIN...CONFIDENCE IN
MEANINGFUL RAINFALL IS TOO LOW FOR MENTION IN THE WX GRIDS ATTM.
GIVEN THAT...MOST OF THE EXTENDED LOOKS DRY ALTHOUGH WE WOULD LOVE
TO BE WRONG ABOUT THAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 61 83 57 85 58 / 20 10 10 20 30
TULIA 63 83 61 85 60 / 20 10 10 10 30
PLAINVIEW 64 82 61 88 63 / 20 10 10 10 30
LEVELLAND 66 83 61 89 63 / 40 20 10 10 30
LUBBOCK 67 84 62 90 65 / 20 20 10 10 30
DENVER CITY 66 84 62 93 63 / 50 20 10 10 20
BROWNFIELD 66 84 62 93 65 / 50 20 10 10 20
CHILDRESS 68 87 64 91 64 / 20 10 0 10 30
SPUR 68 86 65 94 68 / 20 20 10 10 20
ASPERMONT 70 89 67 97 68 / 20 20 10 10 20
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
33/23
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
638 PM CDT SAT AUG 18 2012
.AVIATION...
VFR CONDITIONS EXPECTED FOR KCDS.
FOR KLBB...AN OUTFLOW BOUNDARY TO THE EAST OF KLBB SHOULD MOVE WEST
ACROSS THE TERMINAL IN THE 00Z TO 02Z TIME FRAME WITH TCU AND
POSSIBLY -TSRA IN THE VICINITY OF KLBB. ADDITIONALLY...THERE IS
A LOW PROBABILITY THAT TSRA ACTIVITY CURRENTLY IN THE TX PANHANDLE
COULD MOVE SOUTH AND IMPACT KLBB SOMEWHERE IN THE 03Z TO 09Z TIME
FRAME. OTHERWISE...SURFACE WINDS WILL TEND MORE TO THE NORTHEAST
AND NORTH AS OUTFLOW BOUNDARIES AND A WEAK COLD FRONT MOVE ACROSS
EARLY SUNDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 551 PM CDT SAT AUG 18 2012/
UPDATE...
QUICK UPDATE TO REMOVE HALL...CHILDRESS AND COTTLE COUNTIES FROM
THE SEVERE THUNDERSTORM WATCH. OVERALL...STORM INTENSITY HAS BEEN
RATHER TAME...THOUGH A FEW CELLS DO OCCASIONALLY PULSE UP. IN
ADDITION...A SMALL CLUSTER OF STORMS COULD GENERATE GUSTY WINDS AS
THEY MOVE THROUGH THE SOUTHEASTERN ZONES OVER THE NEXT HALF HOUR
TO HOUR. UPDATED PRODUCTS HAVE BEEN SENT.
PREV DISCUSSION... /ISSUED 339 PM CDT SAT AUG 18 2012/
SHORT TERM...
WELL-DEFINED OUTFLOW BOUNDARY/COMPOSITE COLD FRONT WAS MOVING
SOUTHWEST INTO CHILDRESS AND HALL COUNTIES JUST NORTH OF A SURFACE
TROUGH STRETCHING FROM NEAR DIMMITT ESE TO SWEARINGEN. THE TRUE COLD
FRONT OF INTEREST THAT IS PROGGED TO DROP HIGHS BELOW NORMAL ON
SUNDAY /UNDER MOSTLY SUNNY SKIES!/ WAS FOUND DIVING SOUTH ACROSS WRN
KANSAS AND ERN COLORADO. BRUNT OF THE PRECIP POTENTIAL WILL BE
RELEGATED TO THE PRE-FRONTAL BOUNDARIES CURRENTLY CONVECTING ACROSS
THE NRN HALF OF THE CWA. ALTHOUGH WIND SHEAR IS WEAK THUS FAR...THIS
WILL IMPROVE AS THE AFTERNOON AND EARLY EVENING WEAR ON COURTESY OF
A SHORTWAVE TROUGH AND ASSOCIATED WIND MAX APPROACHING IN NORTHWEST
FLOW. EVEN WITH MLCAPES GENERALLY AOB 1000 J/KG...THIS IMPROVING
LIFT SHOULD SECURE A WINDOW FOR ORGANIZED SEVERE STORMS MAINLY IN
THE FORM OF SMALL SEGMENTS OR LINES WITH DMGG WINDS THE GREATEST
THREAT BEFORE INTENSITY AND STORM COVERAGE WANE BY LATE EVENING.
CURRENT SVR WATCH CAPTURES THIS THREAT WELL...BUT MAY REQUIRE
EXPANSION SWWD SHOULD TRENDS WARRANT. A FEW HI-RES MODELS SUCH AS
THE TTU WRF AND HRRR DO INDICATE SUCH A SCENARIO FOR LUBBOCK AND
POINTS SOUTHWEST...SO THIS WILL BE MONITORED CLOSELY BY THE ONCOMING
SHIFT. OTHERWISE...FROPA WILL OCCUR AFTER MIDNIGHT FOLLOWED BY
DIMINISHING POPS. MOIST POST-FRONTAL UPSLOPE TOMORROW AFTN IN ERN NM
AND ADJACENT COUNTIES OF THE TX SOUTH PLAINS STILL APPEARS
REASONABLE FOR SLIGHT CHANCE POPS IN OUR SWRN COUNTIES...HOWEVER THE
NAM LOOKS MUCH TOO BULLISH WITH QPF IN SUCH A REGIME AND IS LARGELY
BEING DISMISSED
LONG TERM...
NNW FLOW ALOFT IS EXPECTED ON MONDAY. HIGH AMPLITUDE RIDGE WILL
SPAN FROM NWRN MEXICO UP TO NORTHERN ALBERTA. OUT EAST...MATURE LOW
WILL BE SITUATED OVER THE SRN PART OF HUDSON BAY WITH AN EMBEDDED
SHORTWAVE DUE INTO THE CENTRAL PLAINS EARLY ON TUESDAY ALTHOUGH THE
BEST ENERGY ASSOCIATED WITH THIS SYSTEM WILL LIKELY REMAIN NORTHEAST
OF THE REGION. BY MID WEEK...THE RIDGE WILL BEGIN TO MOVE EASTWARD
AND FLATTEN WITH SOME HINTS IN BOTH THE GFS AND ECM ABOUT A BIT OF A
DISTURBANCE PASSING TO OUR NORTH ON THURSDAY. WHILE THE ECM
SOLUTION WOULD BE MORE FAVORABLE INTO BRINGING A FRONT INTO THE
REGION...AND PRECIPITATION...THE GFS HAS MORE CLOSELY PARALLELED
REALITY FOR THE PAST WEEK AND THUS WILL TREND THE FORECAST IN THAT
DIRECTION.
GIVEN NWP PERFORMANCE AS OF LATE WRT QPF AM NOT COMPLETELY CONVINCED
THAT WE WILL SEE AS MUCH RAIN ACROSS THE REGION AS PREVIOUSLY
THOUGHT...BUT HAVE ELECTED ONLY TO MAKE A DOWNWARD TREND OF MONDAY
NIGHT POPS. LIKE TODAY...VIRTUALLY EVERY MODEL CONVECTS BUT PRECIP
HAS BEEN HARD TO COME BY. AS PREVIOUSLY MENTIONED...SHORTWAVE
PASSES TO OUR NORTH SOMETIME ON THURSDAY BUT AGAIN...CONFIDENCE IN
MEANINGFUL RAINFALL IS TOO LOW FOR MENTION IN THE WX GRIDS ATTM.
GIVEN THAT...MOST OF THE EXTENDED LOOKS DRY ALTHOUGH WE WOULD LOVE
TO BE WRONG ABOUT THAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 61 83 57 85 58 / 30 10 10 20 30
TULIA 63 83 61 85 60 / 40 10 10 10 30
PLAINVIEW 64 82 61 88 63 / 50 10 10 10 30
LEVELLAND 66 83 61 89 63 / 50 20 10 10 30
LUBBOCK 67 84 62 90 65 / 50 20 10 10 30
DENVER CITY 66 84 62 93 63 / 40 20 10 10 20
BROWNFIELD 66 84 62 93 65 / 50 20 10 10 20
CHILDRESS 68 87 64 91 64 / 40 10 0 10 30
SPUR 68 86 65 94 68 / 50 20 10 10 20
ASPERMONT 70 89 67 97 68 / 50 20 10 10 20
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
33
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
312 PM CDT FRI AUG 17 2012
.SHORT TERM...
FOR THIS AFTERNOON INTO THIS EVENING...HAVE RAISED POPS A LITTLE
THROUGH THE REST OF THE CONCHO VALLEY. HIGH RESOLUTION RAP SOLUTION
HAS CONVECTION ACROSS THE CONCHO VALLEY THROUGH THE AFTERNOON AND
THEN DEVELOPS MORE CONVECTION ACROSS THE BIG COUNTRY. THE RAP HAS
MORE BROAD CONVECTION ACROSS THE AREA WHILE THE TEXAS TECH 3KM WRF HAS
THE ACTIVITY TOO FAR NORTH. TAKING A LOOK AT SHOWERS AND
THUNDERSTORMS THAT ARE ALREADY FORMING...THE HIGH RESOLUTION RAP MODEL
LOOKS TO BE A BETTER SOLUTION. HAVE NOT CHANGED MUCH THROUGH THE
REST OF TONIGHT AND TOMORROW. MOST OF ACTIVITY LOOKS TO BE
SCATTERED AS IT WILL BE DRIVEN BY MESOSCALE PROCESSES.
REIMER
.LONG TERM...
PRECIPITATION CHANCES WILL CONTINUE THROUGH THE FIRST PART OF THE
EXTENDED FORECAST. A WEAK COLD FRONT THAT IS CURRENTLY STALLED
ACROSS WEST CENTRAL TEXAS WILL REMAIN IN THE VICINITY OF THE AREA
AND BECOME FAIRLY DIFFUSE BY LATE SATURDAY. REGARDLESS...THE FRONT
WILL SERVE AS A FOCUS FOR CONTINUED SHOWERS AND THUNDERSTORMS ACROSS
ALL OF THE REGION SATURDAY NIGHT. SATURDAY...A SHORTWAVE TROUGH WILL
SWING ACROSS THE PLAINS...ALONG THE SOUTHERN PERIPHERY OF THE MAIN
UPPER LEVEL TROUGH THAT IS FORECAST TO BE LOCATED OVER THE MIDWEST.
THIS WILL SEND A REINFORCING SHOT OF SURFACE HIGH PRESSURE DOWN THE
PLAINS AND INTO WEST CENTRAL TEXAS ON SUNDAY. THIS WILL RESULT IN
DECREASING RAIN CHANCES FROM NORTH TO SOUTH THROUGHOUT THE DAY
SUNDAY. I COOLED HIGH TEMPERATURES SUNDAY BY A DEGREE OR TWO...GIVEN
THE EXPECTED CLOUD COVER AND RAINFALL...AND THESE MAY NEED TO
EVENTUALLY BE LOWERED EVEN MORE. SUNDAY NIGHT...RAIN CHANCES WILL BE
CONFINED TO THE CONCHO VALLEY AND AREAS TO THE SOUTH. ALTHOUGH A FEW
STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY NIGHT
THROUGH SUNDAY...THE MAIN THREAT IS THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL.
BEYOND SUNDAY...A SLOW WARMING TREND IS EXPECTED...WITH TEMPERATURES
BACK INTO THE MID 90S BY MID WEEK. MODELS ARE STILL INDICATING A
DISTURBANCE EMBEDDED IN THE NORTHWEST FLOW ALOFT...DROPPING THROUGH
THE TEXAS PANHANDLE MONDAY NIGHT OR TUESDAY. THIS WILL LIKELY RESULT
IN AN MCS DEVELOPING ACROSS THE PANHANDLE AND THEN MOVING SOUTHEAST.
AT THIS TIME...CONFIDENCE IS NOT HIGH ENOUGH IN THIS FEATURE
REACHING WEST CENTRAL TEXAS...SO I HAVE LEFT POPS BELOW 15 PERCENT.
DANIELS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 73 95 71 90 68 / 40 50 50 30 10
SAN ANGELO 74 95 72 91 69 / 30 40 50 40 20
JUNCTION 74 97 72 92 70 / 20 30 40 40 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
REIMER/20/DANIELS
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1213 PM CDT FRI AUG 17 2012
.DISCUSSION...
SEE 18Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
WE WILL SEE VFR CONDITIONS THROUGH THE EARLY AFTERNOON ACROSS THE
AREA. WE STILL EXPECT TO SEE SCATTERED THUNDERSTORMS DEVELOP ALONG
A MESOSCALE BOUNDARY NEAR THE KABI TERMINAL. HOWEVER...THESE
THUNDERSTORMS ARE NOT SUPPOSED TO AFFECT SOUTHERN AREAS UNTIL
LATER ON TONIGHT. MORE WIDESPREAD COVERAGE IS EXPECTED FOR
TOMORROW...HOWEVER...THIS WILL BE SOMEWHAT DEPENDENT ON WHAT
HAPPENS ACROSS THE AREA TONIGHT...AND SO WILL HOLD OFF ON
MENTIONING WX SPECIFICALLY AT ANY ONE SITE FOR NOW...AND INSTEAD
MAY OPT FOR TSRA IN THE VICINITY OF TERMINALS UNTIL MORE
CERTAINTY ON LOCATION IS GAINED. OTHERWISE...WINDS WILL REMAIN OUT
OF THE SOUTH THROUGH THE NEXT 24 HOURS AS THE FRONT WILL NOT BE
ABLE TO PUSH THROUGH THE REGION UNTIL SUNDAY. 20
&&
.PREV DISCUSSION... /ISSUED 637 AM CDT FRI AUG 17 2012/
UPDATE...
SEE 12Z AVIATION DISCUSSION BELOW.
AVIATION...
VFR CONDITIONS SHOULD PREVAIL ACROSS WEST CENTRAL TEXAS TERMINALS
WELL INTO THE AFTERNOON...BEFORE THUNDERSTORMS BEGIN TO DEVELOP
AND CONDITIONS MAY DETERIORATE. MOST LIKELY LOCATION FOR STORMS
WILL BE ACROSS THE BIC COUNTRY...AND HAVE ADDED A VCTS FOR THE
KABI TERMINAL FOR NOW. FARTHER SOUTH...JUST TOO MUCH UNCERTAINTY
ON TIMING AND PLACEMENT OF STORM TO WARRANT A MENTION...BUT
CONDITIONS WILL CERTAINLY NEED TO BE MONITORED.
PREV DISCUSSION... /ISSUED 406 AM CDT FRI AUG 17 2012/
SHORT TERM...
SCATTERED MID LEVEL SHOWERS CONTINUE TO DEVELOP ACROSS PORTIONS OF
THE BIG COUNTRY AND RED RIVER VALLEY EARLY THIS MORNING. ABUNDANT
MID LEVEL MOISTURE COMBINING WITH A LOW LEVEL JET OF 25 TO 30 KTS.
ITS ABOUT THIS TIME THAT CONVECTION EXPANDED YESTERDAY...AND EVEN
WITHOUT THE STRONGER SHORTWAVE THAT WE HAD PASSING...WOULD NOT BE
SURPRISED TO SEE CONVECTIVE COVERAGE EXPAND A LITTLE MORE AT SUNRISE
THIS MORNING AS WELL.
SURFACE FRONTAL BOUNDARY DROPPING THROUGH OKLAHOMA THIS
MORNING...AND SEEMS TO HAVE A DECENT PUSH WITH IT SO FAR.
OBSERVATIONS ARE SHOWING SOME 15 TO 20 KT NORTHEAST WINDS....WITH
DEWPOINTS IN THE 40S AND LOWER 50S. LATEST RUC AS WELL AS THE 4KM
WRF MODEL FROM TEXAS TECH...SHOW THIS BOUNDARY MAKING IT WELL INTO
WEST CENTRAL TEXAS TODAY. IF THIS DOES HAPPEN...THEN CONVECTION WILL
END UP FARTHER SOUTH THAN WE ORIGINALLY THOUGHT. THUS...HAVE BOOSTED
THE POPS ACROSS THE CENTRAL COUNTIES...ROUGHLY BETWEEN ABILENE AND
SAN ANGELO...A LITTLE. THIS ACTIVITY WILL CONTINUE INTO THE
EVENING HOURS.
TONIGHT...MODELS SHOW A STRONGER SHORTWAVE MOVING TOWARDS WEST
CENTRAL TEXAS IN THE NORTHWEST FLOW ALOFT. COMBINE THIS WAVE WITH
WHATS LEFT OF THE SURFACE BOUNDARY...AND EXPECT SCATTERED CONVECTION
TO CONTINUE. WITH THE LOW LEVEL JET STRONGER TONIGHT...BEST POPS
WILL SHIFT A LITTLE TO NORTH OF THE BOUNDARY.
LONG TERM...
LOOKS LIKE A WET PATTERN SETTING UP THIS WEEKEND ACROSS WEST CENTRAL
TEXAS. BENEFICIAL RAINFALL IS NEEDED AS MUCH OF THE CWFA IS
CURRENTLY EXPERIENCING MODERATE TO SEVERE DROUGHT CONDITIONS(AS OF
AUGUST 14)...ACCORDING TO THE US DROUGHT MONITOR. THE MAIN PLAYERS
WILL BE A SLOW MOVING COOL FRONT...OTHER MESOSCALE BOUNDARIES IN THE
AREA AND WEAK UPPER LEVEL FORCING. ALSO...SLOW MOVING STORMS AND
PWAT VALUES OF 1.5 TO 2 INCHES WILL BRING LOCALLY HEAVY RAINFALL.
LOOKS LIKE RAINFALL AMOUNTS WILL AVERAGE 0.5 TO 1.5 INCHES...WITH
LOCALLY HIGHER AMOUNTS POSSIBLE...ESPECIALLY ACROSS THE NORTHERN AND
EASTERN CWFA. ALSO...AN ISOLATED SEVERE STORM OR TWO ARE POSSIBLE
ACROSS THE BIG COUNTRY MAINLY SATURDAY AFTERNOON AND EVENING. THE
MAIN HAZARDS WILL BE LARGE HAIL AND DAMAGING WINDS. THE ABUNDANT
CLOUD COVER AND RAINFALL WILL KEEP TEMPERATURES DOWN SATURDAY AND
SUNDAY. HIGHS WILL BE IN THE UPPER 80S TO MID 90S.
LOOKS LIKE MAINLY DRY WEATHER RETURNING NEXT WEEK AS THE UPPER LEVEL
RIDGE BUILDS BACK OVER THE AREA. THE GFS MODEL IS STILL INDICATING A
POSSIBLE MCS MOVING SOUTHEAST ACROSS THE SOUTHERN PLAINS MONDAY
NIGHT AND TUESDAY MORNING. WILL KEEP THE FORECAST DRY FOR
NOW...HOWEVER WILL NEED TO MONITOR FUTURE MODEL OUTPUT. HIGHS WILL
WARM BACK INTO THE MID 90S EARLY NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 95 72 94 71 90 / 40 40 50 50 40
SAN ANGELO 100 75 95 71 92 / 20 30 40 40 30
JUNCTION 96 74 96 72 94 / 10 20 30 30 30
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
637 AM CDT FRI AUG 17 2012
.UPDATE...
SEE 12Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
VFR CONDITIONS SHOULD PREVAIL ACROSS WEST CENTRAL TEXAS TERMINALS
WELL INTO THE AFTERNOON...BEFORE THUNDERSTORMS BEGIN TO DEVELOP
AND CONDITIONS MAY DETERIORATE. MOST LIKELY LOCATION FOR STORMS
WILL BE ACROSS THE BIC COUNTRY...AND HAVE ADDED A VCTS FOR THE
KABI TERMINAL FOR NOW. FARTHER SOUTH...JUST TOO MUCH UNCERTAINTY
ON TIMING AND PLACEMENT OF STORM TO WARRANT A MENTION...BUT
CONDITIONS WILL CERTAINLY NEED TO BE MONITORED.
&&
.PREV DISCUSSION... /ISSUED 406 AM CDT FRI AUG 17 2012/
SHORT TERM...
SCATTERED MID LEVEL SHOWERS CONTINUE TO DEVELOP ACROSS PORTIONS OF
THE BIG COUNTRY AND RED RIVER VALLEY EARLY THIS MORNING. ABUNDANT
MID LEVEL MOISTURE COMBINING WITH A LOW LEVEL JET OF 25 TO 30 KTS.
ITS ABOUT THIS TIME THAT CONVECTION EXPANDED YESTERDAY...AND EVEN
WITHOUT THE STRONGER SHORTWAVE THAT WE HAD PASSING...WOULD NOT BE
SURPRISED TO SEE CONVECTIVE COVERAGE EXPAND A LITTLE MORE AT SUNRISE
THIS MORNING AS WELL.
SURFACE FRONTAL BOUNDARY DROPPING THROUGH OKLAHOMA THIS
MORNING...AND SEEMS TO HAVE A DECENT PUSH WITH IT SO FAR.
OBSERVATIONS ARE SHOWING SOME 15 TO 20 KT NORTHEAST WINDS....WITH
DEWPOINTS IN THE 40S AND LOWER 50S. LATEST RUC AS WELL AS THE 4KM
WRF MODEL FROM TEXAS TECH...SHOW THIS BOUNDARY MAKING IT WELL INTO
WEST CENTRAL TEXAS TODAY. IF THIS DOES HAPPEN...THEN CONVECTION WILL
END UP FARTHER SOUTH THAN WE ORIGINALLY THOUGHT. THUS...HAVE BOOSTED
THE POPS ACROSS THE CENTRAL COUNTIES...ROUGHLY BETWEEN ABILENE AND
SAN ANGELO...A LITTLE. THIS ACTIVITY WILL CONTINUE INTO THE
EVENING HOURS.
TONIGHT...MODELS SHOW A STRONGER SHORTWAVE MOVING TOWARDS WEST
CENTRAL TEXAS IN THE NORTHWEST FLOW ALOFT. COMBINE THIS WAVE WITH
WHATS LEFT OF THE SURFACE BOUNDARY...AND EXPECT SCATTERED CONVECTION
TO CONTINUE. WITH THE LOW LEVEL JET STRONGER TONIGHT...BEST POPS
WILL SHIFT A LITTLE TO NORTH OF THE BOUNDARY.
LONG TERM...
LOOKS LIKE A WET PATTERN SETTING UP THIS WEEKEND ACROSS WEST CENTRAL
TEXAS. BENEFICIAL RAINFALL IS NEEDED AS MUCH OF THE CWFA IS
CURRENTLY EXPERIENCING MODERATE TO SEVERE DROUGHT CONDITIONS(AS OF
AUGUST 14)...ACCORDING TO THE US DROUGHT MONITOR. THE MAIN PLAYERS
WILL BE A SLOW MOVING COOL FRONT...OTHER MESOSCALE BOUNDARIES IN THE
AREA AND WEAK UPPER LEVEL FORCING. ALSO...SLOW MOVING STORMS AND
PWAT VALUES OF 1.5 TO 2 INCHES WILL BRING LOCALLY HEAVY RAINFALL.
LOOKS LIKE RAINFALL AMOUNTS WILL AVERAGE 0.5 TO 1.5 INCHES...WITH
LOCALLY HIGHER AMOUNTS POSSIBLE...ESPECIALLY ACROSS THE NORTHERN AND
EASTERN CWFA. ALSO...AN ISOLATED SEVERE STORM OR TWO ARE POSSIBLE
ACROSS THE BIG COUNTRY MAINLY SATURDAY AFTERNOON AND EVENING. THE
MAIN HAZARDS WILL BE LARGE HAIL AND DAMAGING WINDS. THE ABUNDANT
CLOUD COVER AND RAINFALL WILL KEEP TEMPERATURES DOWN SATURDAY AND
SUNDAY. HIGHS WILL BE IN THE UPPER 80S TO MID 90S.
LOOKS LIKE MAINLY DRY WEATHER RETURNING NEXT WEEK AS THE UPPER LEVEL
RIDGE BUILDS BACK OVER THE AREA. THE GFS MODEL IS STILL INDICATING A
POSSIBLE MCS MOVING SOUTHEAST ACROSS THE SOUTHERN PLAINS MONDAY
NIGHT AND TUESDAY MORNING. WILL KEEP THE FORECAST DRY FOR
NOW...HOWEVER WILL NEED TO MONITOR FUTURE MODEL OUTPUT. HIGHS WILL
WARM BACK INTO THE MID 90S EARLY NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 95 72 94 71 90 / 40 40 50 50 40
SAN ANGELO 100 75 95 71 92 / 20 30 40 40 30
JUNCTION 96 74 96 72 94 / 10 20 30 30 30
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
406 AM CDT FRI AUG 17 2012
.SHORT TERM...
SCATTERED MID LEVEL SHOWERS CONTINUE TO DEVELOP ACROSS PORTIONS OF
THE BIG COUNTRY AND RED RIVER VALLEY EARLY THIS MORNING. ABUNDANT
MID LEVEL MOISTURE COMBINING WITH A LOW LEVEL JET OF 25 TO 30 KTS.
ITS ABOUT THIS TIME THAT CONVECTION EXPANDED YESTERDAY...AND EVEN
WITHOUT THE STRONGER SHORTWAVE THAT WE HAD PASSING...WOULD NOT BE
SURPRISED TO SEE CONVECTIVE COVERAGE EXPAND A LITTLE MORE AT SUNRISE
THIS MORNING AS WELL.
SURFACE FRONTAL BOUNDARY DROPPING THROUGH OKLAHOMA THIS
MORNING...AND SEEMS TO HAVE A DECENT PUSH WITH IT SO FAR.
OBSERVATIONS ARE SHOWING SOME 15 TO 20 KT NORTHEAST WINDS....WITH
DEWPOINTS IN THE 40S AND LOWER 50S. LATEST RUC AS WELL AS THE 4KM
WRF MODEL FROM TEXAS TECH...SHOW THIS BOUNDARY MAKING IT WELL INTO
WEST CENTRAL TEXAS TODAY. IF THIS DOES HAPPEN...THEN CONVECTION WILL
END UP FARTHER SOUTH THAN WE ORIGINALLY THOUGHT. THUS...HAVE BOOSTED
THE POPS ACROSS THE CENTRAL COUNTIES...ROUGHLY BETWEEN ABILENE AND
SAN ANGELO...A LITTLE. THIS ACTIVITY WILL CONTINUE INTO THE
EVENING HOURS.
TONIGHT...MODELS SHOW A STRONGER SHORTWAVE MOVING TOWARDS WEST
CENTRAL TEXAS IN THE NORTHWEST FLOW ALOFT. COMBINE THIS WAVE WITH
WHATS LEFT OF THE SURFACE BOUNDARY...AND EXPECT SCATTERED CONVECTION
TO CONTINUE. WITH THE LOW LEVEL JET STRONGER TONIGHT...BEST POPS
WILL SHIFT A LITTLE TO NORTH OF THE BOUNDARY.
.LONG TERM...
LOOKS LIKE A WET PATTERN SETTING UP THIS WEEKEND ACROSS WEST CENTRAL
TEXAS. BENEFICIAL RAINFALL IS NEEDED AS MUCH OF THE CWFA IS
CURRENTLY EXPERIENCING MODERATE TO SEVERE DROUGHT CONDITIONS(AS OF
AUGUST 14)...ACCORDING TO THE US DROUGHT MONITOR. THE MAIN PLAYERS
WILL BE A SLOW MOVING COOL FRONT...OTHER MESOSCALE BOUNDARIES IN THE
AREA AND WEAK UPPER LEVEL FORCING. ALSO...SLOW MOVING STORMS AND
PWAT VALUES OF 1.5 TO 2 INCHES WILL BRING LOCALLY HEAVY RAINFALL.
LOOKS LIKE RAINFALL AMOUNTS WILL AVERAGE 0.5 TO 1.5 INCHES...WITH
LOCALLY HIGHER AMOUNTS POSSIBLE...ESPECIALLY ACROSS THE NORTHERN AND
EASTERN CWFA. ALSO...AN ISOLATED SEVERE STORM OR TWO ARE POSSIBLE
ACROSS THE BIG COUNTRY MAINLY SATURDAY AFTERNOON AND EVENING. THE
MAIN HAZARDS WILL BE LARGE HAIL AND DAMAGING WINDS. THE ABUNDANT
CLOUD COVER AND RAINFALL WILL KEEP TEMPERATURES DOWN SATURDAY AND
SUNDAY. HIGHS WILL BE IN THE UPPER 80S TO MID 90S.
LOOKS LIKE MAINLY DRY WEATHER RETURNING NEXT WEEK AS THE UPPER LEVEL
RIDGE BUILDS BACK OVER THE AREA. THE GFS MODEL IS STILL INDICATING A
POSSIBLE MCS MOVING SOUTHEAST ACROSS THE SOUTHERN PLAINS MONDAY
NIGHT AND TUESDAY MORNING. WILL KEEP THE FORECAST DRY FOR
NOW...HOWEVER WILL NEED TO MONITOR FUTURE MODEL OUTPUT. HIGHS WILL
WARM BACK INTO THE MID 90S EARLY NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 95 72 94 71 90 / 40 40 50 50 40
SAN ANGELO 100 75 95 71 92 / 20 30 40 40 30
JUNCTION 96 74 96 72 94 / 10 20 30 30 30
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07/21
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
337 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTHEAST CROSS THE REGION THIS EVENING
INTO TONIGHT ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. DEEPENING
LOW PRESSURE...ANCHORED OVER SOUTHEAST CANADA...WILL EVOLVE ACROSS
THE EASTERN U.S. FOR THE WEEKEND INTO THE FIRST HALF OF NEXT WEEK.
A SERIES OF DISTURBANCES EMBEDDED WITHIN THE UPPER LOW WILL KEEP
UNSETTLED...SHOWERY...CLOUDY...COOL CONDITIONS ACROSS MUCH OF THE
AREA UNTIL TUESDAY...WHEN DRIER CONDITIONS ALONG WITH SEASONABLE
TEMPERATURES ARE EXPECTED.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS 310 PM EDT FRIDAY...
SFC COLD FRONT LOCATED TO OUR WEST FROM WESTERN PENNSYLVANIA
SOUTHWARD TO EASTERN KY. THIS FRONT WILL MOVE SOUTHEAST TONIGHT INTO
SATURDAY. CONVECTION COVERAGE SHOULD INCREASE LATE THIS AFTERNOON
INTO TONIGHT...DUE TO COMBINATION OF DIFFERENTIAL HEATING EFFECTS
AND THE APPROACH OF COLD FRONT/MID-LEVEL SHORT WAVE TROUGH. AT THIS
TIME...REGIONAL WSR-88D IMAGES SHOWED SHOWERS AND ISOLATED
THUNDERSTORMS MOVING EAST ACROSS WESTERN PORTIONS OF CWA. LOOKS LIKE
THE BEST INSTABILITY IS JUST AHEAD OF THE CLOUD DECK. SPC RECENTLY
REMOVED MUCH OF THE AREA FROM THEIR SLIGHT RISK...AND THIS SEEMS
REASONABLE...ESPECIALLY IN LIGHT OF THE WEAK SHEAR OVER THE REGION.
AN ISOLATED STRONG TO SEVERE THUNDERSTORM MAY BE POSSIBLE THIS
EVENING WITH MAIN THREAT HEAVY RAINS AND GUSTY WINDS.
THUNDERSTORMS AND SHOWERS SHOULD WANE/DIMINISH TONIGHT AS THE
UPPER SHORT WAVE SHEARS OUT AND THE MAIN DYNAMICS MOVE TOWARD NEW
ENGLAND. ANOTHER SHORTWAVE POISED THE MOVE ACROSS THE UPPER
MIDWEST/NORTHERN PLAINS OVERNIGHT...WILL PROLONG SW FLOW ALOFT AND
DELAY ANY CLEARING. WITH PLENTY OF CLOUDS TONIGHT...PLAYED LOW
TEMPERATURES CLOSE TO THE ADJMET WITH READINGS FROM AROUND 60
DEGREES IN THE MOUNTAINS TO THE UPPER 60S TO NEAR 70 IN THE
SOUTHEAST.
THE COLD FRONT WILL MOVE SOUTH INTO NORTH CAROLINA FOR SATURDAY.
THERE IS ENOUGH MOISTURE TO COMBINED WITH WEAK UPPER LEVEL
DISTURBANCES AND SURFACE WIND CONVERGENCE TO PRODUCE SHOWERS AND A
FEW THUNDERSTORMS. HIGH TEMPERATURES ON SATURDAY WILL VARY THE MID
70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 320 PM EDT FRIDAY...
COLD FRONT WILL BE DOWN IN THE CAROLINAS BY SAT NIGHT WITH DRIER AND
COOLER AIR SEEPING SOUTHBOUND ALLOWING FOR AN EXODUS OF MOST
LEFTOVER SHRA OVER THE SOUTH SAT EVENING. NEXT MID LEVEL IMPULSE
PROGGED BY MOST MODELS WILL ROUND THE 5H TROF SLIDING THRU THE UPPER
MIDWEST SUNDAY AND DAMPEN UPON PASSING INTO THE OHIO VALLEY SUNDAY
NIGHT. DEEPER MOISTURE WITH THE RESIDUAL FRONT LOOKS TO REMAIN JUST
SOUTH OF THE CWA THOUGH AS OVERALL MID LEVEL BACKING OF THE FLOW
AHEAD OF THE WAVE APPEARS WEAK ATTM. HOWEVER WITH LOW LEVEL
TRAJECTORIES TURNING MORE SOUTH/SE AND A RIBBON OF HIGHER SFC-85H
THETA-E SPREADING ALONG/EAST OF THE BLUE RIDGE...WENT AHEAD AND
EXPANDED THE CHANCE POPS NORTH SUNDAY/SUNDAY EVENING...WITH BEST
COVERAGE SOUTHERN HALF WHERE SOME CAPE WILL EXIST. SHRA MAY LINGER
EAST SUNDAY NIGHT AND BUBBLE BACK TO THE WEST ON MONDAY AS YET
ANOTHER UPPER LEVEL DISTURBANCE SPINS BY AND PERHAPS INDUCES A SFC
WAVE ALONG THE FRONT TO THE SOUTH MONDAY AFTERNOON PER THE LASTEST
CANADIAN. AGAIN MAINLY MIDDLE RANGE CHANCE POPS FOR NOW GIVEN
UNCERTAINTY AND ONLY SLIGHT POPS FAR WEST/NW WHERE REMOVED FROM THE
DEEPER RH. OTRW MORE CLOUDS SOUTH/EAST AND PERHAPS MORE
BREAKS/CLEARING AT TIMES NORTH-NW THRU MONDAY. CLOUDS/SHRA SHOULD
KEEP HIGHS MAINLY IN THE 70S TO LOW 80S WITH LOWS 50S TO LOW 60S
MOUNTAINS...AND 60-65 BEHIND THE FRONT OUT EAST.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 1215 PM EDT FRIDAY...
UPPER TROF ACROSS THE EAST WILL GRADUALLY WEAKEN AND START TO LIFT
OUT BY LATE IN THE WEEK AS WEAK SURFACE HIGH PRESSURE REMAINS IN
PLACE. HOWEVER MODELS SUGGEST THAT A 5H IMPULSE ROTATING AROUND THE
DEPARTING TROFFINESS THRU THE MID MISS VALLEY...COULD EVOLVE INTO A
WEAK UPPER LOW BY MID WEEK WHICH MAY SLIP EAST INTO THE CENTRAL
APPALACHIANS BY FRIDAY. THIS QUITE UNCERTAIN AND MAINLY SUPPORTED BY
THE LATEST ECMWF...BUT WOULD BE ENOUGH TO LIKELY ENHANCE CONVECTIVE
CHANCES LATER IN THE WEEK DESPITE WEAK RIDGING IN PLACE. OTRW TREND
IN THE OVERALL FORECAST REMAINS ON THE DRY SIDE WITH THE RESIDUAL
AXIS OF DEEPER MOISTURE STILL TO THE SE...AND CONTINUED DRIER NORTH
TO NE FLOW IN PLACE. THIS LOW LEVEL ONSHORE FLOW COULD BRING IN SOME
LOW CLOUDS TO ALONG THE BLUE RIDGE AT TIMES DURING THE OVERNIGHTS
BUT IFFY. OTRW INTERVALS OF CLOUDS AND SUN THRU THE PERIOD WITH MAINLY
DIURNALLY DRIVEN SLIGHT CHANCE CONVECTIVE POPS ESPCLY SW AND
MOUNTAINS WHERE AIDED BY LOCAL CONVERGENCE. COVERAGE PERHAPS A BIT
MORE LATE IN THE WEEK OVER THE SOUTH IF THE WEAK CUTOFF DEVELOPS AND
BETTER MOISTURE GETS RETURNED NORTH. TEMPS MAINLY PERSISTENCE THRU
THE PERIOD UNDER HIGH PRESSURE/LIGHT WINDS...AND ONLY SLIGHT WARMING
ALOFT...WITH HIGHS 70S TO ARND 80 MOUNTAINS AND LOW/MID 80S EAST.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 105 PM EDT FRIDAY...
MAIN FOCUS FOR TAF VALID PERIOD IS CHANCE FOR CONVECTION THIS
AFTERNOON/EVENING. REGIONAL WSR-88D LOOP SHOWED SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS MOVING EAST ACROSS THE WESTERN MOUNTAINS.
LOOKS LIKE THE BEST INSTABILITY JUST IN FRONT OF THE CLOUD BLANKET.
COLD FRONT LOCATED TO OUR WEST ALONG THE OHIO RIVER WILL MOVE EAST
ACROSS OUR REGION WITH SCATTERED MVFR SHOWERS AND THUNDERSTORM.
LOCAL IFR CONDITIONS AND GUSTY WINDS POSSIBLE WITH A STRONGER
STORM. ACCORDING TO THE HRRR AND LOCAL WRFARW-RNK LOOKS LIKE THE
BEST CHANCE FOR A THUNDERSTORM MAY BE AT BLF OR DAN. HOWEVER
THUNDERSTORMS ARE POSSIBLE AT ALL TAF SITES THIS AFTERNOON INTO
TONIGHT WITH COLD FRONT MOVING ACROSS THE REGION.
ANOTHER CONCERN IS WHETHER OR NOT CLOUDS/PCPN WILL EXIT THE AREA...OR
BUILD BACK NORTHWARD OVERNIGHT IN WAKE OF INITIAL WAVE OF
SHRA/TSRA. KEPT MVFR CLOUDS-CIGS AND MVFR-IFR VSBYS IN -RA/-SHRA/-DZ AFT
08Z. THINKING IS THAT -SHRA WILL GENERALLY BE CONFINED TO PIEDMONT
REGION...BUT UPSLOPE FLOW AND PASSING WAVE ALONG FRONT TO THE
SOUTH COULD PROMOTE DEVELOPMENT OF LOW CLOUDS AND -DZ BLF-LWB AFT
08Z SAT. WINDS REMAIN W-NW THROUGH TAF VALID PERIOD...BUT WILL BE
VEERING OVER TO NE NEAR 12Z SAT...WHICH WILL FURTHER PROMOTE
DEVELOPMENT OF LOW CLOUDS AND FOG...ESPECIALLY ACROSS THE PIEDMONT
REGION.
EXTENDED AVIATION DISCUSSION...
THE FRONT SLOWS AND LINGERS ACROSS THE CAROLINAS THROUGH THE
WEEKEND...WHILE HIGH PRESSURE PASSES EASTWARD TO THE SOUTH OF THE
GREAT LAKES. EXPECT MOST OF THE AREA TO REMAIN DRY ON
SATURDAY...HOWEVER WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP MAINLY ACROSS THE MOUNTAINS WITH AFTERNOON HEATING FROM
SUNDAY INTO THE MIDDLE OF NEXT WEEK.
&&
.EQUIPMENT...
KFCX RADAR IS BACK UP AND RUNNING...BUT MAY GO DOWN AGAIN
TONIGHT. PROBLEMS WITH KLYSTRON BLOWER MOTOR. PARTS ON ORDER.
ESTIMATED REPLACEMENT OF PART AFTER DELIVERY ON SATURDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...KK/RAB
NEAR TERM...KK
SHORT TERM...JH
LONG TERM...JH
AVIATION...KK/RAB
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
124 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION THIS AFTERNOON ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS INTO THIS EVENING. DEEPENING LOW
PRESSURE...ANCHORED OVER SOUTHEAST CANADA...WILL EVOLVE ACROSS THE
EASTERN U.S. FOR THE WEEKEND INTO THE FIRST HALF OF NEXT WEEK. A
SERIES OF DISTURBANCES EMBEDDED WITHIN THE UPPER LOW WILL KEEP
UNSETTLED...SHOWERY...CLOUDY...COOL CONDITIONS ACROSS MUCH OF THE
AREA UNTIL TUESDAY...WHEN DRIER CONDITIONS ALONG WITH SEASONABLE
TEMPERATURES ARE EXPECTED.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS 104 PM EDT FRIDAY...
REGIONAL WSR-88D IMAGES SHOWED SHOWERS AND ISOLATED THUNDERSTORMS
MOVING EAST INTO WESTERN PORTIONS OF CWA. CLOUD SHIELD SPREADING
EAST ACROSS THE WESTERN MOUNTAINS HINDER THUNDERSTORM DEVELOPMENT.
SWODY1 HAS BACK OFF ON SEVERE POTENTIAL WITH A SEE TEXT ACROSS OUR
REGION. ISOLATED STRONG TO SEVERE THUNDERSTORMS MAY STILL BE
POSSIBLE THIS AFTERNOON WITH COLD FRONT AND UPPER LEVEL VORT
ROTATING EAST ACROSS OUR AREA. ADJUSTED CLOUDS...TEMPERATURES AND
POPS FOR THIS AFTERNOON. MORE LATER THIS AFTERNOON...
AS OF 940 AM EDT FRIDAY...
LOW CLOUDS AND FOG ARE LIFTING AS HIGH CLOUDS SPREAD EAST INTO OUR
REGION. EXPECT SUFFICIENT HEATING COMBINED WITH LOW-LEVEL MOISTURE
INCREASE TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT. SWODY1 HAS KEPT WESTERN PORTIONS OF CWA IN SLIGHT
RISK OF SEVERE FOR THIS AFTERNOON. THE MAIN THREAT IS FOR DAMAGING
WINDS. HRRR AND WRF-ARWRNK SHOWED CONVECTION STARTING AFTER 19Z
AND MOVES EAST INTO TONIGHT. MODIFIED CLOUD COVER AND POPS FOR
THIS MORNING INTO THIS AFTERNOON. ADJUSTED TEMPERATURES ACCORDING
TO LATEST OBS AND MODEL TRENDS. MADE A LITTLE COOLER IN THE WEST
WITH ADDITIONAL LOW CLOUDS THIS MORNING.
AS OF 500 AM EDT FRIDAY...
MAIN CONCERN THROUGH THE SHORT TERM WILL BE APPROACHING SHORT
WAVE...NOW LOCATED FROM THE EASTERN GREAT LAKES SWWD INTO OK/MO.
AN OVERNIGHT MCS ASSOCIATED WITH THIS TROUGH BACKBUILT
SOUTHWESTWARD INTO THE MID-SOUTH/LOWER MS VALLEY REGION...WITH
LITTLE TO NO ACTIVITY CURRENT EVIDENT FURTHER NORTH ACROSS THE OH
VALLEY. THIS SHORT WAVE WILL PROGRESS TOWARD THE MID-ATLANTIC BY
00Z AND EVOLVE INTO A DEEPENING AREA OF SEMI-PERMANENT UPPER LOW
PRESSURE ALOFT ACROSS SOUTHEAST CANADA THROUGH THE WEEKEND AND
INTO EARLY NEXT WEEK. IN SO DOING...DYNAMICS WILL WEAKEN AS THE
SYSTEM PROGRESSES TOWARD THE EAST COAST. EXTENSIVE MID-HIGH CLOUDS
HAVE SPREAD EASTWARD ACROSS THE OH VALLEY INTO PARTS OF WV EARLY
THIS MORNING...BUT THE LACK OF UPSTREAM CONVECTION SUPPORTS
CURRENT THINKING THAT ANTECEDENT CLOUD COVER ACROSS OUR CWA WILL
BE LIMITED ENOUGH TO ALLOW SUFFICIENT HEATING COMBINED WITH A SLOW
LOW-LEVEL MOISTURE INCREASE TO SUPPORT SCT SHRA/TSRA BY MID-DAY
THROUGH THE EVENING FROM W-E. SPC HAS OUTLOOKED THE ENTIRE CWA FOR
SLIGHT RISK FOR MULTI-CELL TSRA WITH SPOTTY MARGINAL HAIL AND
DAMAGING WINDS. MODEL PROGGED INSTABILITY IS WEAK AT BEST AND SHEAR
IS NIL...SO LOCAL THINKING IS THAT A 5 PERCENT RISK OF SEVERE MAY
BE SUFFICIENT TO COVER EXPECTED CONVECTIVE ACTIVITY TODAY. CERTAINLY
CANNOT RULE OUT A WARNING OR TWO DURING THE AFTERNOON/EARLY
EVENING...ESPECIALLY ACROSS THE SOUTHERN SHENANDOAH VALLEY...FAR
SOUTHWEST VA...AND NORTHERN PIEDMONT REGION. ACTIVITY SHOULD WANE
RATHER QUICKLY AFT 00Z AS THE UPPER SHORT WAVE SHEARS OUT AND THE
MAIN DYNAMICS MOVE TOWARD NEW ENGLAND. ALTHOUGH SHRA/TSRA ACTIVITY
SHOULD GENERALLY DISSIPATE ACROSS E/SE SECTIONS OF THE CWA AFT
06Z...EMBEDDED UPSTREAM SHORT WAVES...PARTICULARLY ONE POISED
ACROSS THE UPPER MIDWEST/NORTHERN PLAINS OVERNIGHT...WILL PROLONG
SW FLOW ALOFT AND DELAY ANY CLEARING DURING THE REMAINDER OF THE
NEAR TERM.
MAX TEMPS TODAY WILL BE PROBLEMATIC AND COULD EASILY VARY BY AS
MUCH AS 20F OR MORE FROM THE WV SIDE OF THE CWA TO THE SE PIEDMONT
REGION. EXTENSIVE MID-HIGH CLOUDS SHOULD SPREAD ACROSS AREAS
ALONG-W OF THE ALLEGHANYS EARLY ENOUGH IN THE DAY TO GREATLY LIMIT
DAYTIME HEATING ACROSS THOSE AREAS...WITH SHRA/TSRA DEVELOPING
WEST OF A ROA-HLX-HKY LINE BY 18Z. EAST OF THIS AREA...CLOUDS WILL
BE SLOWER TO ARRIVE WITH INITIAL SFC MOISTURE LIMITING EARLY CU
DEVELOPMENT. WITH 850MB TEMPS NEAR +18C BY AFTERNOON...ALBEIT 2C
COOLER THAN INDICATED ACROSS THAT REGION YESTERDAY...AREAS FROM
LYH-DAN EASTWARD COULD EASILY APPROACH 90 BY AFTERNOON.
THUS...HAVE MAX TEMPS RANGING FROM THE MID 70S SE WV TO AROUND DAN
AND POINTS EASTWARD. RADIATIONAL COOLING OVERNIGHT WILL BE MINIMAL
TO NONE WITH EXTENSIVE CLOUD COVER REMAINING IN PLACE. DEWPOINTS
WILL REMAIN IN THE 60S TO EVEN NEAR 70 ACROSS THE SE PIEDMONT
REGION. THUS...EXPECT MIN TEMPS TO GENERALLY BE AOA THIS MORNINGS
READINGS WITH LESS VARIATION NOTED...RANGING FROM THE LOW 60S
MOUNTAINS/SE WV TO NEAR 70 DAN AND POINTS EASTWARD.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 430 AM THURSDAY...
ALTHOUGH THE COLD FRONT WILL REMAIN ACROSS NORTH CAROLINA FOR MOST
OF THE WEEKEND...ENOUGH MOISTURE WILL COMBINE WITH WEAK UPPER LEVEL
DISTURBANCES AND SURFACE WIND CONVERGENCE TO PRODUCE SHOWERS AND A
FEW STORMS MOSTLY SOUTH OF RT 460...THROUGH THE PERIOD. TEMPS WILL
BE NOTICEABLY COOLER AND ATTM SUNDAY SEEMS TO HAVE THE MOST COVERAGE
OF SHOWERS ROUGHLY FROM TNB TO HLX. H85 TEMPS FROM +12C TO +14C WITH
CLOUDS AND OFF ON AND SHOWERS SHOULD PUT MAX T IN THE MIDDLE 70S TO
LOWER 80S ACROSS THE CWA.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 1215 PM EDT FRIDAY...
UPPER TROF ACROSS THE EAST WILL GRADUALLY WEAKEN AND START TO LIFT
OUT BY LATE IN THE WEEK AS WEAK SURFACE HIGH PRESSURE REMAINS IN
PLACE. HOWEVER MODELS SUGGEST THAT A 5H IMPULSE ROTATING AROUND THE
DEPARTING TROFFINESS THRU THE MID MISS VALLEY...COULD EVOLVE INTO A
WEAK UPPER LOW BY MID WEEK WHICH MAY SLIP EAST INTO THE CENTRAL
APPALACHIANS BY FRIDAY. THIS QUITE UNCERTAIN AND MAINLY SUPPORTED BY
THE LATEST ECMWF...BUT WOULD BE ENOUGH TO LIKELY ENHANCE CONVECTIVE
CHANCES LATER IN THE WEEK DESPITE WEAK RIDGING IN PLACE. OTRW TREND
IN THE OVERALL FORECAST REMAINS ON THE DRY SIDE WITH THE RESIDUAL
AXIS OF DEEPER MOISTURE STILL TO THE SE...AND CONTINUED DRIER NORTH
TO NE FLOW IN PLACE. THIS LOW LEVEL ONSHORE FLOW COULD BRING IN SOME
LOW CLOUDS TO ALONG THE BLUE RIDGE AT TIMES DURING THE OVERNIGHTS
BUT IFFY. OTRW INTERVALS OF CLOUDS AND SUN THRU THE PERIOD WITH MAINLY
DIURNALLY DRIVEN SLIGHT CHANCE CONVECTIVE POPS ESPCLY SW AND
MOUNTAINS WHERE AIDED BY LOCAL CONVERGENCE. COVERAGE PERHAPS A BIT
MORE LATE IN THE WEEK OVER THE SOUTH IF THE WEAK CUTOFF DEVELOPS AND
BETTER MOISTURE GETS RETURNED NORTH. TEMPS MAINLY PERSISTENCE THRU
THE PERIOD UNDER HIGH PRESSURE/LIGHT WINDS...AND ONLY SLIGHT WARMING
ALOFT...WITH HIGHS 70S TO ARND 80 MOUNTAINS AND LOW/MID 80S EAST.
&&
.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
AS OF 105 PM EDT FRIDAY...
MAIN FOCUS FOR TAF VALID PERIOD IS CHANCE FOR CONVECTION THIS
AFTERNOON/EVENING. REGIONAL WSR-88D LOOP SHOWED SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS MOVING EAST ACROSS THE WESTERN MOUNTAINS.
LOOKS LIKE THE BEST INSTABILITY JUST IN FRONT OF THE CLOUD BLANKET.
COLD FRONT LOCATED TO OUR WEST ALONG THE OHIO RIVER WILL MOVE EAST
ACROSS OUR REGION WITH SCATTERED MVFR SHOWERS AND THUNDERSTORM.
LOCALL IFR CONDITIONS AND GUSTY WINDS POSSIBLE WITH A STRONGER
STORM. ACCORDING TO THE HRRR AND LOCAL WRFARW-RNK LOOKS LIKE THE
BEST CHANCE FOR A THUNDERSTORM MAY BE AT BLF OR DAN. HOWEVER
THUNDERSTORMS ARE POSSIBLE AT ALL TAF SITES THIS AFTERNOON INTO
TONIGHT WITH COLD FRONT MOVING ACROSS THE REGION.
ANOTHER CONCERN IS WHETHER OR NOT CLOUDS/PCPN WILL EXIT THE AREA...OR
BUILD BACK NORTHWARD OVERNIGHT IN WAKE OF INITIAL WAVE OF
SHRA/TSRA. KEPT MVFR CLOUDS-CIGS AND MVFR-IFR VSBYS IN -RA/-SHRA/-DZ AFT
08Z. THINKING IS THAT -SHRA WILL GENERALLY BE CONFINED TO PIEDMONT
REGION...BUT UPSLOPE FLOW AND PASSING WAVE ALONG FRONT TO THE
SOUTH COULD PROMOTE DEVELOPMENT OF LOW CLOUDS AND -DZ BLF-LWB AFT
08Z SAT. WINDS REMAIN W-NW THROUGH TAF VALID PERIOD...BUT WILL BE
VEERING OVER TO NE NEAR 12Z SAT...WHICH WILL FURTHER PROMOTE
DEVELOPMENT OF LOW CLOUDS AND FOG...ESPECIALLY ACROSS THE PIEDMONT
REGION.
EXTENDED AVIATION DISCUSSION...
THE FRONT SLOWS AND LINGERS ACROSS THE CAROLINAS THROUGH THE
WEEKEND...WHILE HIGH PRESSURE PASSES EASTWARD TO THE SOUTH OF THE
GREAT LAKES. EXPECT MOST OF THE AREA TO REMAIN DRY ON
SATURDAY...HOWEVER WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP MAINLY ACROSS THE MOUNTAINS WITH AFTERNOON HEATING FROM
SUNDAY INTO THE MIDDLE OF NEXT WEEK.
&&
.EQUIPMENT...
KFCX RADAR IS DOWN. KLYSTRON BLOWER MOTOR HAS FAILED. PARTS ON ORDER.
ESTIMATED RTS ABOUT 2015Z OR 415 PM SATURDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...KK/RAB
NEAR TERM...RAB
SHORT TERM...KM
LONG TERM...JH
AVIATION...KK/RAB
EQUIPMENT...KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1223 PM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TODAY ACCOMPANIED BY SHOWERS
AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING. DEEPENING LOW
PRESSURE...ANCHORED OVER SOUTHEAST CANADA...WILL EVOLVE ACROSS THE
EASTERN U.S. FOR THE WEEKEND INTO THE FIRST HALF OF NEXT WEEK. A
SERIES OF DISTURBANCES EMBEDDED WITHIN THE UPPER LOW WILL KEEP
UNSETTLED...SHOWERY...CLOUDY...COOL CONDITIONS ACROSS MUCH OF THE
AREA UNTIL TUESDAY...WHEN DRIER CONDITIONS ALONG WITH SEASONABLE
TEMPERATURES ARE EXPECTED.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 940 AM EDT FRIDAY...
LOW CLOUDS AND FOG ARE LIFTING AS HIGH CLOUDS SPREAD EAST INTO OUR
REGION. EXPECT SUFFICIENT HEATING COMBINED WITH LOW-LEVEL MOISTURE
INCREASE TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT. SWODY1 HAS KEPT WESTERN PORTIONS OF CWA IN SLIGHT
RISK OF SEVERE FOR THIS AFTERNOON. THE MAIN THREAT IS FOR DAMAGING
WINDS. HRRR AND WRF-ARWRNK SHOWED CONVECTION STARTING AFTER 19Z
AND MOVES EAST INTO TONIGHT. MODIFIED CLOUD COVER AND POPS FOR
THIS MORNING INTO THIS AFTERNOON. ADJUSTED TEMPERATURES ACCORDING
TO LATEST OBS AND MODEL TRENDS. MADE A LITTLE COOLER IN THE WEST
WITH ADDITIONAL LOW CLOUDS THIS MORNING.
AS OF 500 AM EDT FRIDAY...
MAIN CONCERN THROUGH THE SHORT TERM WILL BE APPROACHING SHORT
WAVE...NOW LOCATED FROM THE EASTERN GREAT LAKES SWWD INTO OK/MO.
AN OVERNIGHT MCS ASSOCIATED WITH THIS TROUGH BACKBUILT
SOUTHWESTWARD INTO THE MID-SOUTH/LOWER MS VALLEY REGION...WITH
LITTLE TO NO ACTIVITY CURRENT EVIDENT FURTHER NORTH ACROSS THE OH
VALLEY. THIS SHORT WAVE WILL PROGRESS TOWARD THE MID-ATLANTIC BY
00Z AND EVOLVE INTO A DEEPENING AREA OF SEMI-PERMANENT UPPER LOW
PRESSURE ALOFT ACROSS SOUTHEAST CANADA THROUGH THE WEEKEND AND
INTO EARLY NEXT WEEK. IN SO DOING...DYNAMICS WILL WEAKEN AS THE
SYSTEM PROGRESSES TOWARD THE EAST COAST. EXTENSIVE MID-HIGH CLOUDS
HAVE SPREAD EASTWARD ACROSS THE OH VALLEY INTO PARTS OF WV EARLY
THIS MORNING...BUT THE LACK OF UPSTREAM CONVECTION SUPPORTS
CURRENT THINKING THAT ANTECEDENT CLOUD COVER ACROSS OUR CWA WILL
BE LIMITED ENOUGH TO ALLOW SUFFICIENT HEATING COMBINED WITH A SLOW
LOW-LEVEL MOISTURE INCREASE TO SUPPORT SCT SHRA/TSRA BY MID-DAY
THROUGH THE EVENING FROM W-E. SPC HAS OUTLOOKED THE ENTIRE CWA FOR
SLIGHT RISK FOR MULTI-CELL TSRA WITH SPOTTY MARGINAL HAIL AND
DAMAGING WINDS. MODEL PROGGED INSTABILITY IS WEAK AT BEST AND SHEAR
IS NIL...SO LOCAL THINKING IS THAT A 5 PERCENT RISK OF SEVERE MAY
BE SUFFICIENT TO COVER EXPECTED CONVECTIVE ACTIVITY TODAY. CERTAINLY
CANNOT RULE OUT A WARNING OR TWO DURING THE AFTERNOON/EARLY
EVENING...ESPECIALLY ACROSS THE SOUTHERN SHENANDOAH VALLEY...FAR
SOUTHWEST VA...AND NORTHERN PIEDMONT REGION. ACTIVITY SHOULD WANE
RATHER QUICKLY AFT 00Z AS THE UPPER SHORT WAVE SHEARS OUT AND THE
MAIN DYNAMICS MOVE TOWARD NEW ENGLAND. ALTHOUGH SHRA/TSRA ACTIVITY
SHOULD GENERALLY DISSIPATE ACROSS E/SE SECTIONS OF THE CWA AFT
06Z...EMBEDDED UPSTREAM SHORT WAVES...PARTICULARLY ONE POISED
ACROSS THE UPPER MIDWEST/NORTHERN PLAINS OVERNIGHT...WILL PROLONG
SW FLOW ALOFT AND DELAY ANY CLEARING DURING THE REMAINDER OF THE
NEAR TERM.
MAX TEMPS TODAY WILL BE PROBLEMATIC AND COULD EASILY VARY BY AS
MUCH AS 20F OR MORE FROM THE WV SIDE OF THE CWA TO THE SE PIEDMONT
REGION. EXTENSIVE MID-HIGH CLOUDS SHOULD SPREAD ACROSS AREAS
ALONG-W OF THE ALLEGHANYS EARLY ENOUGH IN THE DAY TO GREATLY LIMIT
DAYTIME HEATING ACROSS THOSE AREAS...WITH SHRA/TSRA DEVELOPING
WEST OF A ROA-HLX-HKY LINE BY 18Z. EAST OF THIS AREA...CLOUDS WILL
BE SLOWER TO ARRIVE WITH INITIAL SFC MOISTURE LIMITING EARLY CU
DEVELOPMENT. WITH 850MB TEMPS NEAR +18C BY AFTERNOON...ALBEIT 2C
COOLER THAN INDICATED ACROSS THAT REGION YESTERDAY...AREAS FROM
LYH-DAN EASTWARD COULD EASILY APPROACH 90 BY AFTERNOON.
THUS...HAVE MAX TEMPS RANGING FROM THE MID 70S SE WV TO AROUND DAN
AND POINTS EASTWARD. RADIATIONAL COOLING OVERNIGHT WILL BE MINIMAL
TO NONE WITH EXTENSIVE CLOUD COVER REMAINING IN PLACE. DEWPOINTS
WILL REMAIN IN THE 60S TO EVEN NEAR 70 ACROSS THE SE PIEDMONT
REGION. THUS...EXPECT MIN TEMPS TO GENERALLY BE AOA THIS MORNINGS
READINGS WITH LESS VARIATION NOTED...RANGING FROM THE LOW 60S
MOUNTAINS/SE WV TO NEAR 70 DAN AND POINTS EASTWARD.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 430 AM THURSDAY...
ALTHOUGH THE COLD FRONT WILL REMAIN ACROSS NORTH CAROLINA FOR MOST
OF THE WEEKEND...ENOUGH MOISTURE WILL COMBINE WITH WEAK UPPER LEVEL
DISTURBANCES AND SURFACE WIND CONVERGENCE TO PRODUCE SHOWERS AND A
FEW STORMS MOSTLY SOUTH OF RT 460...THROUGH THE PERIOD. TEMPS WILL
BE NOTICEABLY COOLER AND ATTM SUNDAY SEEMS TO HAVE THE MOST COVERAGE
OF SHOWERS ROUGHLY FROM TNB TO HLX. H85 TEMPS FROM +12C TO +14C WITH
CLOUDS AND OFF ON AND SHOWERS SHOULD PUT MAX T IN THE MIDDLE 70S TO
LOWER 80S ACROSS THE CWA.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 1215 PM EDT FRIDAY...
UPPER TROF ACROSS THE EAST WILL GRADUALLY WEAKEN AND START TO LIFT
OUT BY LATE IN THE WEEK AS WEAK SURFACE HIGH PRESSURE REMAINS IN
PLACE. HOWEVER MODELS SUGGEST THAT A 5H IMPULSE ROTATING AROUND THE
DEPARTING TROFFINESS THRU THE MID MISS VALLEY...COULD EVOLVE INTO A
WEAK UPPER LOW BY MID WEEK WHICH MAY SLIP EAST INTO THE CENTRAL
APPALACHIANS BY FRIDAY. THIS QUITE UNCERTAIN AND MAINLY SUPPORTED BY
THE LATEST ECMWF...BUT WOULD BE ENOUGH TO LIKELY ENHANCE CONVECTIVE
CHANCES LATER IN THE WEEK DESPITE WEAK RIDGING IN PLACE. OTRW TREND
IN THE OVERALL FORECAST REMAINS ON THE DRY SIDE WITH THE RESIDUAL
AXIS OF DEEPER MOISTURE STILL TO THE SE...AND CONTINUED DRIER NORTH
TO NE FLOW IN PLACE. THIS LOW LEVEL ONSHORE FLOW COULD BRING IN SOME
LOW CLOUDS TO ALONG THE BLUE RIDGE AT TIMES DURING THE OVERNIGHTS
BUT IFFY. OTRW INTERVALS OF CLOUDS AND SUN THRU THE PERIOD WITH MAINLY
DIURNALLY DRIVEN SLIGHT CHANCE CONVECTIVE POPS ESPCLY SW AND
MOUNTAINS WHERE AIDED BY LOCAL CONVERGENCE. COVERAGE PERHAPS A BIT
MORE LATE IN THE WEEK OVER THE SOUTH IF THE WEAK CUTOFF DEVELOPS AND
BETTER MOISTURE GETS RETURNED NORTH. TEMPS MAINLY PERSISTENCE THRU
THE PERIOD UNDER HIGH PRESSURE/LIGHT WINDS...AND ONLY SLIGHT WARMING
ALOFT...WITH HIGHS 70S TO ARND 80 MOUNTAINS AND LOW/MID 80S EAST.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 740 AM EDT FRIDAY...
IMMEDIATE CONCERN IS LOCALIZED POCKETS OF IFR-LIFR CIGS/VSBYS IN FG
AT THE USUAL SPOTS...NAMELY LWB AND BCB. THIS SHOULD DISSIPATE
QUICKLY...BUT MAY HANG ON FOR A LITTLE WHILE AT LWB BECAUSE OF
REDUCED INSOLATION FROM INCREASING HIGH CLOUDS. WILL NEED TO WATCH
FOR DEVELOPMENT OF MVFR CIGS BLF-LWB AS WELL AS FOG LIFTS INTO
STRATUS DECK. STRATUS ALREADY EVIDENT JUST TO THE WEST OF BLF. AS
NOTED BEFORE...MAIN FOCUS FOR TAF VALID PERIOD IS CHANCE FOR
CONVECTION THIS AFTERNOON/EVENING. NEW CONCERN IS WHETHER OR NOT
CLOUDS/PCPN WILL EXIT THE AREA...OR BUILD BACK NORTHWARD OVERNIGHT
IN WAKE OF INITIAL WAVE OF SHRA/TSRA. NO CHANGES AT THIS TIME TO
EARLIER INDICATED CONVECTIVE TIMING...MAINLY 18Z LWB-BLF TO 00Z
LYH-DAN. BIGGEST CHANGE WAS TO ADD MVFR CIGS AND MVFR-IFR VSBYS IN
-RA/-SHRA/-DZ AFT 08Z. THINKING IS THAT -SHRA WILL GENERALLY BE
CONFINED TO PIEDMONT REGION...BUT UPSLOPE FLOW AND PASSING WAVE
ALONG FRONT TO THE SOUTH COULD PROMOTE DEVELOPMENT OF LOW CLOUDS AND
-DZ BLF-LWB AFT 08Z SAT. WINDS REMAIN W-NW THROUGH TAF VALID
PERIOD...BUT WILL BE VEERING OVER TO NE NEAR 12Z SAT...WHICH WILL
FURTHER PROMOTE DEVELOPMENT OF LOW CLOUDS AND FOG...ESPECIALLY
ACROSS THE PIEDMONT REGION.
AS OF 200 AM EDT FRIDAY...
MAIN CONCERN THROUGH TAF VALID PERIOD WILL BE APPROACHING/DEEPENING
UPPER TROUGH AND ASSOCIATED FRONTAL SYSTEM. VFR CONDITIONS IN PLACE
ACROSS THE CWA AT THIS HOUR WITH CONSIDERABLY LESS FOG EVIDENT THAN
AT THIS TIME YESTERDAY...LARGELY THANKS TO EXPANDING AREA OF HIGH
CLOUDS AS EXPECTED. NONETHELESS...SEVERAL HOURS OF MVFR CAN BE
EXPECTED AT BCB/LWB FOR SURE THROUGH 13Z...BUT ANY IFR CONDITIONS
SHOULD BE BRIEF/ISOLD. MODELS IN GENERAL AGREEMENT WITH RESPECT TO
TIMING OF CONVECTION. EXPECT CONVECTION TO DEVELOP LWB-BLF IN THE
18Z TIME FRAME...THEN SPREAD EAST TOWARD THE PIEDMONT BY 00Z.
GENERALLY MVFR CIGS/VSBYS EXPECTED WITH SHRA/TSRA...WITH ISOLD/BRIEF
IFR CONDITIONS TOO UNCERTAIN TO PUT IN PREVAILING OR TEMPO GROUPS AT
THIS TIME. WINDS WILL REMAIN WSW-WNW THROUGH TAF VALID PERIOD...WITH
SPEEDS REMAINING LESS THAN 10KTS.
EXTENDED AVIATION DISCUSSION...
THE FRONT SLOWS AND LINGERS ACROSS THE CAROLINAS THROUGH THE
WEEKEND...WHILE HIGH PRESSURE PASSES EASTWARD TO THE SOUTH OF THE
GREAT LAKES. EXPECT MOST OF THE AREA TO REMAIN DRY ON
SATURDAY...HOWEVER WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP MAINLY ACROSS THE MOUNTAINS WITH AFTERNOON HEATING FROM
SUNDAY INTO THE MIDDLE OF NEXT WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...KK/RAB
NEAR TERM...RAB
SHORT TERM...KM
LONG TERM...JH
AVIATION...RAB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
950 AM EDT FRI AUG 17 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION TODAY ACCOMPANIED BY SHOWERS
AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING. DEEPENING LOW
PRESSURE...ANCHORED OVER SOUTHEAST CANADA...WILL EVOLVE ACROSS THE
EASTERN U.S. FOR THE WEEKEND INTO THE FIRST HALF OF NEXT WEEK. A
SERIES OF DISTURBANCES EMBEDDED WITHIN THE UPPER LOW WILL KEEP
UNSETTLED...SHOWERY...CLOUDY...COOL CONDITIONS ACROSS MUCH OF THE
AREA UNTIL TUESDAY...WHEN DRIER CONDITIONS ALONG WITH SEASONABLE
TEMPERATURES ARE EXPECTED.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 940 AM EDT FRIDAY...
LOW CLOUDS AND FOG ARE LIFTING AS HIGH CLOUDS SPREAD EAST INTO OUR
REGION. EXPECT SUFFICIENT HEATING COMBINED WITH LOW-LEVEL MOISTURE
INCREASE TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT. SWODY1 HAS KEPT WESTERN PORTIONS OF CWA IN SLIGHT
RISK OF SEVERE FOR THIS AFTERNOON. THE MAIN THREAT IS FOR DAMAGING
WINDS. HRRR AND WRF-ARWRNK SHOWED CONVECTION STARTING AFTER 19Z
AND MOVES EAST INTO TONIGHT. MODIFIED CLOUD COVER AND POPS FOR
THIS MORNING INTO THIS AFTERNOON. ADJUSTED TEMPERATURES ACCORDING
TO LATEST OBS AND MODEL TRENDS. MADE A LITTLE COOLER IN THE WEST
WITH ADDITIONAL LOW CLOUDS THIS MORNING.
AS OF 500 AM EDT FRIDAY...
MAIN CONCERN THROUGH THE SHORT TERM WILL BE APPROACHING SHORT
WAVE...NOW LOCATED FROM THE EASTERN GREAT LAKES SWWD INTO OK/MO.
AN OVERNIGHT MCS ASSOCIATED WITH THIS TROUGH BACKBUILT
SOUTHWESTWARD INTO THE MID-SOUTH/LOWER MS VALLEY REGION...WITH
LITTLE TO NO ACTIVITY CURRENT EVIDENT FURTHER NORTH ACROSS THE OH
VALLEY. THIS SHORT WAVE WILL PROGRESS TOWARD THE MID-ATLANTIC BY
00Z AND EVOLVE INTO A DEEPENING AREA OF SEMI-PERMANENT UPPER LOW
PRESSURE ALOFT ACROSS SOUTHEAST CANADA THROUGH THE WEEKEND AND
INTO EARLY NEXT WEEK. IN SO DOING...DYNAMICS WILL WEAKEN AS THE
SYSTEM PROGRESSES TOWARD THE EAST COAST. EXTENSIVE MID-HIGH CLOUDS
HAVE SPREAD EASTWARD ACROSS THE OH VALLEY INTO PARTS OF WV EARLY
THIS MORNING...BUT THE LACK OF UPSTREAM CONVECTION SUPPORTS
CURRENT THINKING THAT ANTECEDENT CLOUD COVER ACROSS OUR CWA WILL
BE LIMITED ENOUGH TO ALLOW SUFFICIENT HEATING COMBINED WITH A SLOW
LOW-LEVEL MOISTURE INCREASE TO SUPPORT SCT SHRA/TSRA BY MID-DAY
THROUGH THE EVENING FROM W-E. SPC HAS OUTLOOKED THE ENTIRE CWA FOR
SLIGHT RISK FOR MULTI-CELL TSRA WITH SPOTTY MARGINAL HAIL AND
DAMAGING WINDS. MODEL PROGGED INSTABILITY IS WEAK AT BEST AND SHEAR
IS NIL...SO LOCAL THINKING IS THAT A 5 PERCENT RISK OF SEVERE MAY
BE SUFFICIENT TO COVER EXPECTED CONVECTIVE ACTIVITY TODAY. CERTAINLY
CANNOT RULE OUT A WARNING OR TWO DURING THE AFTERNOON/EARLY
EVENING...ESPECIALLY ACROSS THE SOUTHERN SHENANDOAH VALLEY...FAR
SOUTHWEST VA...AND NORTHERN PIEDMONT REGION. ACTIVITY SHOULD WANE
RATHER QUICKLY AFT 00Z AS THE UPPER SHORT WAVE SHEARS OUT AND THE
MAIN DYNAMICS MOVE TOWARD NEW ENGLAND. ALTHOUGH SHRA/TSRA ACTIVITY
SHOULD GENERALLY DISSIPATE ACROSS E/SE SECTIONS OF THE CWA AFT
06Z...EMBEDDED UPSTREAM SHORT WAVES...PARTICULARLY ONE POISED
ACROSS THE UPPER MIDWEST/NORTHERN PLAINS OVERNIGHT...WILL PROLONG
SW FLOW ALOFT AND DELAY ANY CLEARING DURING THE REMAINDER OF THE
NEAR TERM.
MAX TEMPS TODAY WILL BE PROBLEMATIC AND COULD EASILY VARY BY AS
MUCH AS 20F OR MORE FROM THE WV SIDE OF THE CWA TO THE SE PIEDMONT
REGION. EXTENSIVE MID-HIGH CLOUDS SHOULD SPREAD ACROSS AREAS
ALONG-W OF THE ALLEGHANYS EARLY ENOUGH IN THE DAY TO GREATLY LIMIT
DAYTIME HEATING ACROSS THOSE AREAS...WITH SHRA/TSRA DEVELOPING
WEST OF A ROA-HLX-HKY LINE BY 18Z. EAST OF THIS AREA...CLOUDS WILL
BE SLOWER TO ARRIVE WITH INITIAL SFC MOISTURE LIMITING EARLY CU
DEVELOPMENT. WITH 850MB TEMPS NEAR +18C BY AFTERNOON...ALBEIT 2C
COOLER THAN INDICATED ACROSS THAT REGION YESTERDAY...AREAS FROM
LYH-DAN EASTWARD COULD EASILY APPROACH 90 BY AFTERNOON.
THUS...HAVE MAX TEMPS RANGING FROM THE MID 70S SE WV TO AROUND DAN
AND POINTS EASTWARD. RADIATIONAL COOLING OVERNIGHT WILL BE MINIMAL
TO NONE WITH EXTENSIVE CLOUD COVER REMAINING IN PLACE. DEWPOINTS
WILL REMAIN IN THE 60S TO EVEN NEAR 70 ACROSS THE SE PIEDMONT
REGION. THUS...EXPECT MIN TEMPS TO GENERALLY BE AOA THIS MORNINGS
READINGS WITH LESS VARIATION NOTED...RANGING FROM THE LOW 60S
MOUNTAINS/SE WV TO NEAR 70 DAN AND POINTS EASTWARD.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
AS OF 430 AM THURSDAY...
ALTHOUGH THE COLD FRONT WILL REMAIN ACROSS NORTH CAROLINA FOR MOST
OF THE WEEKEND...ENOUGH MOISTURE WILL COMBINE WITH WEAK UPPER LEVEL
DISTURBANCES AND SURFACE WIND CONVERGENCE TO PRODUCE SHOWERS AND A
FEW STORMS MOSTLY SOUTH OF RT 460...THROUGH THE PERIOD. TEMPS WILL
BE NOTICEABLY COOLER AND ATTM SUNDAY SEEMS TO HAVE THE MOST COVERAGE
OF SHOWERS ROUGHLY FROM TNB TO HLX. H85 TEMPS FROM +12C TO +14C WITH
CLOUDS AND OFF ON AND SHOWERS SHOULD PUT MAX T IN THE MIDDLE 70S TO
LOWER 80S ACROSS THE CWA.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 350 PM THURSDAY...
UPPER LEVEL TROF GRADUALLY FILLS DURING THE WEEK WITH MODERATING
HEIGHTS AND THICKNESSES. THIS SHOULD RESULT IN GRADUAL RETURN OF
SOUTHERLY LOW LEVEL FLOW...AND A MORE DIURNALLY DRIVEN CONVECTIVE
REGIME WITH DAYTIME CU AND NIGHTTIME CLEARING. ANY PRECIP THREAT
WOULD BE MAINLY CONFINED TO THE PEAK HEATING PART OF THE DAY AND
PRIMARILY CONFINED TO THE MTNS WHERE LOW LEVEL CONVERGENCE WOULD
BE GREATEST. TEMPERATURES ARE EXPECTED TO BE THE COOLEST EARLY IN
THE WEEK...5 DEG BLOW NORM...THEN TREND CLOSER TO NORMAL FOR MID
WEEK.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AS OF 740 AM EDT FRIDAY...
IMMEDIATE CONCERN IS LOCALIZED POCKETS OF IFR-LIFR CIGS/VSBYS IN FG
AT THE USUAL SPOTS...NAMELY LWB AND BCB. THIS SHOULD DISSIPATE
QUICKLY...BUT MAY HANG ON FOR A LITTLE WHILE AT LWB BECAUSE OF
REDUCED INSOLATION FROM INCREASING HIGH CLOUDS. WILL NEED TO WATCH
FOR DEVELOPMENT OF MVFR CIGS BLF-LWB AS WELL AS FOG LIFTS INTO
STRATUS DECK. STRATUS ALREADY EVIDENT JUST TO THE WEST OF BLF. AS
NOTED BEFORE...MAIN FOCUS FOR TAF VALID PERIOD IS CHANCE FOR
CONVECTION THIS AFTERNOON/EVENING. NEW CONCERN IS WHETHER OR NOT
CLOUDS/PCPN WILL EXIT THE AREA...OR BUILD BACK NORTHWARD OVERNIGHT
IN WAKE OF INITIAL WAVE OF SHRA/TSRA. NO CHANGES AT THIS TIME TO
EARLIER INDICATED CONVECTIVE TIMING...MAINLY 18Z LWB-BLF TO 00Z
LYH-DAN. BIGGEST CHANGE WAS TO ADD MVFR CIGS AND MVFR-IFR VSBYS IN
-RA/-SHRA/-DZ AFT 08Z. THINKING IS THAT -SHRA WILL GENERALLY BE
CONFINED TO PIEDMONT REGION...BUT UPSLOPE FLOW AND PASSING WAVE
ALONG FRONT TO THE SOUTH COULD PROMOTE DEVELOPMENT OF LOW CLOUDS AND
-DZ BLF-LWB AFT 08Z SAT. WINDS REMAIN W-NW THROUGH TAF VALID
PERIOD...BUT WILL BE VEERING OVER TO NE NEAR 12Z SAT...WHICH WILL
FURTHER PROMOTE DEVELOPMENT OF LOW CLOUDS AND FOG...ESPECIALLY
ACROSS THE PIEDMONT REGION.
AS OF 200 AM EDT FRIDAY...
MAIN CONCERN THROUGH TAF VALID PERIOD WILL BE APPROACHING/DEEPENING
UPPER TROUGH AND ASSOCIATED FRONTAL SYSTEM. VFR CONDITIONS IN PLACE
ACROSS THE CWA AT THIS HOUR WITH CONSIDERABLY LESS FOG EVIDENT THAN
AT THIS TIME YESTERDAY...LARGELY THANKS TO EXPANDING AREA OF HIGH
CLOUDS AS EXPECTED. NONETHELESS...SEVERAL HOURS OF MVFR CAN BE
EXPECTED AT BCB/LWB FOR SURE THROUGH 13Z...BUT ANY IFR CONDITIONS
SHOULD BE BRIEF/ISOLD. MODELS IN GENERAL AGREEMENT WITH RESPECT TO
TIMING OF CONVECTION. EXPECT CONVECTION TO DEVELOP LWB-BLF IN THE
18Z TIME FRAME...THEN SPREAD EAST TOWARD THE PIEDMONT BY 00Z.
GENERALLY MVFR CIGS/VSBYS EXPECTED WITH SHRA/TSRA...WITH ISOLD/BRIEF
IFR CONDITIONS TOO UNCERTAIN TO PUT IN PREVAILING OR TEMPO GROUPS AT
THIS TIME. WINDS WILL REMAIN WSW-WNW THROUGH TAF VALID PERIOD...WITH
SPEEDS REMAINING LESS THAN 10KTS.
EXTENDED AVIATION DISCUSSION...
THE FRONT SLOWS AND LINGERS ACROSS THE CAROLINAS THROUGH THE
WEEKEND...WHILE HIGH PRESSURE PASSES EASTWARD TO THE SOUTH OF THE
GREAT LAKES. EXPECT MOST OF THE AREA TO REMAIN DRY ON
SATURDAY...HOWEVER WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP MAINLY ACROSS THE MOUNTAINS WITH AFTERNOON HEATING FROM
SUNDAY INTO THE MIDDLE OF NEXT WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...KK/RAB
NEAR TERM...RAB
SHORT TERM...KM
LONG TERM...PM
AVIATION...RAB
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
902 PM CDT SAT AUG 18 2012
.UPDATE...
LARGE AREA OF CLOUDS ACROSS IOWA/ILLINOIS AND SOUTHERN WISCONSIN
TIED MAINLY TO OLD CONVECTION DEBRIS FROM SHORTWAVE OVER CENTRAL
PLAINS. 00Z 500 MB CHART SHOWS LARGE AREA OF 40 METER FALLS FROM
OMA ON SOUTH INTO TOP/SGF AREAS AND THAT SHOULD SWING SOUTH OF
WISCONSIN.
DIURNAL CONVECTION BENEATH UPPER CYCLONIC FLOW IN NORTHERN
WISCONSIN AND MINNESOTA HAS BEEN DECREASING. HRRR KEEPS SOME OF
THIS GOING ALL NIGHT BENEATH -18 TO -19C COLD POCKET...BUT KEEPS
SOUTHERN WISCONSIN DRY.
OF MORE INTEREST IS POTENTIAL FOR REPEAT OF WATERSPOUTS. SEE
MARINE DISCUSSION FOR THAT ITEM.
925 MP TEMPS AROUND +17C AT 00Z. ALTHOUGH MORE HIGH CLOUDINESS
AROUND TONIGHT STILL SHOULD SEE MODERATE NOCTURNAL INVERSION WHICH
SUGGESTS LOWER TO MIDDLE 50S AND THAT IS WHAT IS IN THE FORECAST.
&&
.AVIATION/06Z TAFS/...
SHOULD BE VFR WITH LIGHT WINDS OVERNIGHT AND MAINLY JUST HIGH
CLOUDS. MODELS IN EXCELLENT AGREEMENT IN SCATTERED SHOWERS AND
THUNDERSTORMS DURING THE MIDDAY AND AFTERNOON ACROSS SOUTHERN
WISCONSIN... JUST LIKE WHAT WE SAW IN NORTHERN WISCONSIN SATURDAY
AFTERNOON. IMPACTS SHOULD BE BRIEF AT ANY ONE AIRPORT...BUT
CERTAINLY COULD SEE MVFR CONDITIONS FOR LESS THAN AN HOUR.
&&
.MARINE...
APPEARS THAT WATERSPOUT EVENT THIS MORNING MAY JUST BE THE
BEGINNING OF TWO MORE POTENTIAL EVENTS SUNDAY AND MONDAY. 00Z
UPPER AIR DATA SHOWS 850 MB TEMPS OF +9C AT APX AND INL...WHICH
WOULD REPRESENT A DELTA T OF 13C. THIS MORNINGS EVENT HAD DELTA T
OF 14C...BUT ONLY A SURFACE BASED LI OF -3. NAM SHOWS LIS AROUND
-5 SUNDAY MORNING EAST OF MILWAUKEE ALONG WITH A LOW LEVEL
CONVERGENCE ZONE. NON SUPERCELL TORNADO PARAMETER BECOMES QUITE
HIGH AT 16 IN THAT AREA...COMPARED TO THE VALUE OF 2 THAT WE SAW
THIS MORNING WHEN NUMBEROUS WATERSPOUTS WERE SIGHTED ABOUT 50-60
MILES SOUTHEAST OF MILWAUKEE.
ANOTHER WEAK CIRCULATION AND TROUGH IS SHOWN AGAIN EARLY MONDAY
OVER SOUTH LAKE MICHIGAN WITH LIS OF -3 TO -4 AND A NON SUPERCELL
TORNADO PARAMETER OF ABOUT 6. SO WILL BEEF UP MENTION OF
WATERSPOUTS BOTH SUNDAY AND MONDAY.
&&
.PREV DISCUSSION... /ISSUED 246 PM CDT SAT AUG 18 2012/
TONIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
DIURNAL CUMULUS CLOUDS SHOULD SLOWLY DISSIPATE AT OR SOON AFTER
SUNSET ACROSS THE AREA...WITH LOSS OF DAYTIME HEATING. SOME MIDDLE
TO HIGH CLOUDS WILL LINGER FROM TIME TO TIME THIS EVENING...BEFORE
MORE MOVES INTO THE AREA FROM THE NORTHERN MINNESOTA LATER TONIGHT
INTO SUNDAY. LIGHT AND VARIABLE WINDS TONIGHT WITH SOME CLOUDS
SHOULD KEEP LOWS IN THE LOWER TO MID 50S.
WEAK COLD FRONT SLIDES SOUTH THROUGH THE AREA ON SUNDAY. WEAK LOW
LEVEL FRONTOGENESIS RESPONSE SEEN ON NAM...LESS SO ON GFS. AREA
FORECAST SOUNDINGS FROM NAM SUGGEST TALL BUT SKINNY MEAN LAYER CAPES
OF A FEW HUNDRED J/KG DEVELOPING DURING THE DAY. PASSING BOUNDARY
WITH DAYTIME HEATING SHOULD BE ENOUGH TO BRING ISOLATED TO
SCATTERED SHOWERS...WITH AN ISOLATED THUNDERSTORM. MORE DIURNAL
CUMULUS SHOULD DEVELOP DURING THE DAY AS WELL. HIGHS SHOULD REACH
THE MID 70S IN MOST LOCATIONS...WITH TEMPERATURES TURNING A BIT
COOLER LAKESIDE WITH ONSHORE WINDS IN THE AFTERNOON.
SUNDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
EXPECT A RAPID DIMINISHING OF ANY SHOWERS THAT DEVELOP SUNDAY
AFTERNOON. WILL HANG ONTO A SMALL CHANCE ACROSS THE FAR SOUTH
DURING THE EARLY EVENING FOR ANY LINGERERS. DELTA T/S ACROSS LAKE
MICHIGAN SHOULD BE RUNNING ABOUT 13C. A RATHER SIGNIFICANT THERMAL
TROF WILL BE MOVING OVER THE WESTERN GREAT LAKES WITH LAKE ADJUSTED
CAPES SUGGESTING CONVECTION COULD REACH 25-30KFT OVER THE LAKE.
WILL CARRY A SLGT CHANCE OF LAKE EFFECT THUNDERSTORMS.
MONDAY...FORECAST CONFIDENCE IS MEDIUM.
HAVE INTRODUCED A SLIGHT CHANCE OF SHOWERS OVER THE SOUTHEAST.
LOOKS LIKE WE WILL SEE A MARINE LAYER WITH HIGHER DEWPOINTS ADVECT
INLAND. COUPLE THIS WITH THOSE COLD TEMPS ALOFT...STEEP LOW/MID
LEVEL LAPSE RATES...AND A WEAK LAKE BREEZE POSSIBLY BRINGING JUST
ENOUGH LOW LEVEL CONVERGENCE...AND WE COULD SEE SOME AFTERNOON
SHOWERS.
MONDAY NIGHT AND BEYOND...FORECAST CONFIDENCE MEDIUM TO HIGH.
STILL LOOKS QUIET FOR MOST OF NEXT WEEK...ALONG WITH A GRADUAL
WARMING TREND. THE NEXT CHANCE FOR RAIN MIGHT BE AT THE END OF THE
WEEK AS BOTH THE GFS AND THE ECMWF SHOW A WEAKENING TROF MOVING
IN. HOWEVER...THE ECMWF HAS MOST OF THE SYSTEM PASSING TO OUR
SOUTH...JUST CLIPPING THE REGION WITH LIGHT QPF.
AVIATION/00Z TAFS/...
VFR CONDITIONS EXPECTED THROUGH SUNDAY ACROSS TAF SITES. SHOULD SEE
SCATTERED DIURNAL CUMULUS CLOUDS DISSIPATE BY EARLY EVENING WITH
LOSS OF DAYTIME HEATING. SOME MIDDLE TO HIGH CLOUDS SHOULD LINGER AT
TIMES THIS EVENING. SOUTHEAST WINDS WITH LAKE BREEZE SHOULD REACH
MILWAUKEE AND KENOSHA AFTER 20Z...LINGERING UNTIL SUNSET.
LIGHT AND VARIABLE WINDS ARE EXPECTED TONIGHT...WITH SOME MIDDLE TO
HIGH CLOUDS MOVING INTO THE AREA LATER IN THE NIGHT INTO SUNDAY.
WEAK COLD FRONT WILL SHIFT SOUTH THROUGH THE AREA SUNDAY. DIURNAL
CUMULUS EXPECTED TO DEVELOP AGAIN BY AFTERNOON...WITH ISOLATED TO
SCATTERED SHOWERS EXPECTED. WILL MENTION VICINITY SHOWERS IN TAFS
FOR NOW DUE TO SCATTERED NATURE. LIGHT WINDS EXPECTED AGAIN ON
SUNDAY...SHIFTING NORTHEAST AT EASTERN TAF SITES IN THE AFTERNOON.
,MARINE...
WEAK COLD FRONT PASSES SOUTHWARD ACROSS THE NEARSHORE WATERS SUNDAY.
EXPECTED DELTA T VALUES WITH EXTRAPOLATED CONVECTIVE CLOUD DEPTH
SUGGEST AN OUTSIDE SHOT AT WATERSPOUTS SUNDAY MORNING AS THE FRONT
SLIDES THROUGH. SWI INDEX ALSO SHOWS FAVORABLE CONDITIONS LASTING
ALL DAY SUNDAY. FOR NOW...WILL INCLUDE ISOLATED WATERSPOUT WORDING
IN FORECAST SUNDAY MORNING. CONDITIONS COULD LINGER THROUGH THE
DAY...SO WILL CONTINUE TO MONITOR.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...CRAVEN
TONIGHT/SUNDAY AND AVIATION/MARINE...WOOD
SUNDAY NIGHT THROUGH SATURDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
331 PM CDT FRI AUG 17 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
331 PM CDT FRI AUG 17 2012
AT 3 PM...A 1020 MB SURFACE HIGH WAS CENTERED OVER SOUTHWEST
MINNESOTA AND NORTHWEST IOWA. THERE WAS ALSO A SURFACE TROUGH
NOTED IN THE WIND DATA FROM WISCONSIN RAPIDS TO ROCHESTER
MINNESOTA. WITH LITTLE MOISTURE ACROSS THE AREA...THIS FRONT IS
ONLY PRODUCING A WIND SHIFT WITH ITS PASSAGE. FURTHER ALOFT...A
SHORT WAVE TROUGH LOCATED OVER CENTRAL NORTH DAKOTA WAS PRODUCING
SOME SCATTERED TO BROKEN HIGH CLOUDS ACROSS THE AREA.
TONIGHT...THE MAIN QUESTION IS HOW WIDESPREAD THE VALLEY FOG MAY
BECOME. THE MODEL SOUNDINGS CONTINUE TO SHOW THAT THERE WILL BE
LIGHT WINDS UP TO 750 MB. THEY ALSO SHOW THAT THE SKIES WILL BE
MOSTLY CLEAR WHICH WILL ALLOW GOOD RADIATIVE COOLING. THE ONE
NEGATIVE AND IT IS A BIG ONE IS THAT THE SOUNDINGS CONTINUE TO
SHOW THAT THE BOUNDARY LAYER REMAINS VERY DRY. THIS IS IN DESPITE
THE UNSEASONABLY COOL TEMPERATURES /IN THE 40S/ OVER THE WARM /LOW
TO MID 70/ RIVERS WHICH IS USUALLY VERY CONDUCIVE TO THE
DEVELOPMENT OF STEAM/VALLEY FOG. THE DIURNAL MIXING THIS AFTERNOON
HAS ALLOWED DRY AIR FROM ALOFT TO MIX DOWN TO THE SURFACE. THIS
HAS CAUSED OUR DEW POINTS TO FALL ANYWHERE FROM 10 TO 15 DEGREES
TODAY. WITH DEW POINTS CURRENTLY IN THE MID 30S TO MID 40S...THERE
IS CONCERN THAT THE DEW POINTS WILL NOT RECOVER ENOUGH TONIGHT TO
ALLOW THE VALLEY FOG TO FORM. A LOCAL COMPOSITE STUDY FOR KLSE
SHOWS THAT IF THE TEMPERATURE/DEW POINT SPREAD IS MORE THAN 7
DEGREES AT 03Z...THAT THE PROBABILITIES OF DENSE FOG /QUARTER MILE
OR LESS/ DRAMATICALLY DECREASE. SINCE WE ARE STILL A BIT UNSURE
HOW MUCH RECOVERY THERE WILL BE IN THE DEW POINTS TONIGHT...KEPT
THE AREAS OF VALLEY FOG IN THE FORECAST FOR TONIGHT. THE ONLY
CHANGE AT THIS TIME WAS DELAY THE ONSET FROM 18.06Z TO 18.09Z.
ON SATURDAY...A TROUGH OF LOW PRESSURE WILL MOVE SOUTH INTO
NORTHERN MINNESOTA AND NORTHERN WISCONSIN. AHEAD OF THE FORMER
SYSTEM...THE MODELS INDICATE THAT WITH DIURNAL HEATING...THE ML
CAPES WILL CLIMB UP TO 300 J/KG NORTH OF THE INTERSTATE 94
CORRIDOR. THIS WILL BE ENOUGH INSTABILITY TO WARRANT A SMALL
CHANCE /15 TO 24 PERCENT/ OF PRECIPITATION DURING THE AFTERNOON
AND EVENING. EVEN THOUGH THE MODELS MIGHT SUGGEST A HIGHER
PRECIPITATION CHANCE...WAS CONCERNED THAT THE MODEL SOUNDINGS
SUGGESTED THE POSSIBILITY THAT THE DEW POINTS ONCE AGAIN FALL INTO
THE 40S ON SATURDAY AFTERNOON. IF THIS OCCURRED...THERE WOULD NOT
BE ENOUGH INSTABILITY TO GENERATE ANY PRECIPITATION. AS A
RESULT...KEPT THE PRECIPITATION CHANCES ON THE LOW SIDE.
ON SATURDAY NIGHT...THE MODELS CONTINUE TO SUGGEST THAT THE
TROUGH ACROSS NORTHERN MINNESOTA AND NORTHERN WISCONSIN WILL MOVE
SOUTHEAST TO THE INTERSTATE 90 CORRIDOR. AT THIS TIME...IT LOOKS
LIKE THIS SYSTEM WILL ONLY BRING SOME MID AND HIGH CLOUDS TO THE
AREA. THESE CLOUDS WILL LIMIT THE COOLING SOME...SO KEPT THE
VALLEY FOG OUT OF THE FORECAST.
ON SUNDAY...THE MODELS CONTINUE TO SUGGEST THAT THE CAPES MAY
CLIMB UP TO 500 J/KG ACROSS SOUTHERN WISCONSIN. AS A RESULT...
KEPT A CHANCE OF SHOWERS IN THE FORECAST. HOWEVER LIKE
SATURDAY...THERE IS SOME QUESTIONS ON WHETHER THE DEW POINTS ARE
TOO HIGH...SO KEPT THE MENTION OF THUNDER OUT OF THE FORECAST.
.LONG TERM...MONDAY THROUGH FRIDAY
331 PM CDT FRI AUG 17 2012
FROM MONDAY THROUGH THURSDAY...THE MODELS STILL SHOW THAT THE
UPPER LEVEL RIDGE OVER THE ROCKIES WILL MOVE EASTWARD AND FLATTEN
AS A SERIES OF SHORT WAVE TROUGHS OVERRUN IT. LIKE THE ECMWF OVER
THE PAST 2 DAYS...THE GFS NOW SHOWS THAT THESE SYSTEMS WILL BE
MUCH FURTHER NORTH. AS A RESULT...WENT WITH A DRY FORECAST FOR
THIS TIME PERIOD. IN ADDITION...WITH MORE SUNSHINE EXPECTED
BOOSTED TEMPERATURES A BIT.
ON THURSDAY NIGHT AND FRIDAY...THE GFS SHOWS THAT A COLD FRONT
WILL MOVE EAST THROUGH THE AREA. MEANWHILE ECMWF KEEPS THE RIDGE
INTACT DURING THIS TIME PERIOD. SINCE THE ECMWF TYPICALLY DOES THE
BEST...JUST WENT WITH A DRY FORECAST.
&&
.AVIATION...THROUGH 18Z SATURDAY
1213 PM CDT FRI AUG 17 2012
THE MAIN CONCERN THROUGH SATURDAY MORNING IS WHETHER VALLEY FOG
WILL FORM AND RESTRICT THE VISIBILITY AT KLSE. THE 17.12Z NAM AND
17.15Z RAP CONTINUE TO SHOW SOME SIGNALS THAT THE VALLEY FOG IS
NOT A CERTAINTY TO FORM. WHILE THE SURFACE HIGH WILL BE OVER THE
AREA TO PROVIDE CLEAR SKIES AND LIGHT WINDS THROUGH A DEEP
LAYER...THE CONCERN IS WHETHER SATURATION WILL OCCUR. DEW POINTS
THIS AFTERNOON ARE EXPECTED TO MIX OUT INTO THE LOWER TO MIDDLE
40S AND THEN RECOVER AROUND 5 DEGREES DURING THE EVENING. NEITHER
THE NAM OR THE RAP SHOW ENOUGH RECOVERY IN THE DEW POINT OR
COOLING OF THE SURFACE TEMPERATURES TO ALLOW SATURATION TO OCCUR.
THE SHORT TERM LAV GUIDANCE WHICH IS USUALLY AGGRESSIVE WITH THE
FORMATION OF FOG AND VISIBILITY RESTRICTION ALSO DOES NOT SHOW ANY
FOG FORMING DESPITE ONLY HAVING A 1 TO 2 DEGREE TEMP/DEW POINT
SPREAD LATE TONIGHT. THUS WITH MIXED SIGNALS...HAVE NOT MADE ANY
CHANGES TO THE FORECAST FOR KLSE. STILL FEEL THERE WILL BE SOME
VALLEY FOG THAT FORMS...BUT WITH CONCERNS ON HOW MUCH...LEFT THE
VISIBILITY MVFR WITH THE INCLUSION OF BCFG. NO CONCERNS AT KRST
THROUGH 18Z SATURDAY WITH VFR CONDITIONS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
331 PM CDT FRI AUG 17 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1214 PM CDT FRI AUG 17 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
230 AM CDT FRI AUG 17 2012
FORECAST CONCERNS FOCUS ON THE PCPN POTENTIAL WITH A WEATHER SYSTEM
TRACKING ACROSS THE REGION SAT-SUN.
A SHORTWAVE TROUGH WILL DROP SOUTHWARD OUT OF CANADA...SLIDING
ACROSS THE NORTHERN PLAINS AND ACROSS IA/ILL. ITS CURRENT TRACK
WOULD KEEP ANY ASSOCIATED PCPN CHANCES WEST/SOUTH OF THE FORECAST
AREA. HOWEVER...IT WILL ALSO HELP CARVE OUT THE BROAD UPPER LEVEL
TROUGH A BIT MORE...WHICH WILL ALLOW ANOTHER PIECE OF ENERGY TO SLIP
ACROSS NORTHERN PARTS OF THE REGION SAT AFTERNOON/EVENING. THIS
UPPER LEVEL FEATURE ALSO LOOKS TO HAVE A REFLECTION AT THE SFC...AND
THERE IS SOME WEAK LOW LEVEL FRONTOGENETIC FORCING WITH IT. THE
17.00Z NAM PAINTS AROUND 500 J/KG OF MUCAPE AROUND THIS BOUNDARY
WHILE A NORTH-SOUTH RUNNING X-SECTION POINTS TO A DECENT AMOUNT OF
SATURATION IN THE 700-500 MB FOR THE FORCING/INSTABILITY TO WORK ON.
THE NAM/GFS/GEM/ECMWF ALL DEPICT SOME LIGHT PCPN WITH THIS
SYSTEM...MOSTLY FROM CENTRAL MN ACROSS NORTHERN WI. CLOUD BASES
WOULD PROBABLY BE RATHER HIGH...BUT THERE HAS BEEN A LOT OF 8-10 KFT
OVER THE PAST FEW WEEKS THAT HAVE BEEN PRODUCING PCPN...DESPITE SOME
INDICATIONS OF A DRY NEAR SFC LAYER. BELIEVE THERE IS ENOUGH FORCING
TO WORK ON THE SATURATION FOR AT LEAST SMALL PCPN CHANCES. PROBABLY
MORE SHOWERS...BUT CAN/T RULE OUT ISOLATED THUNDER.
THE SFC BOUNDARY WILL SAG SOUTH SAT NIGHT...SLIDING ACROSS SOUTHERN
WI ON SUNDAY. COULD BE ENOUGH FORCING AROUND THE FRONT TO SPARK MORE
SHOWER CHANCES. SOUTHERN WI/NORTHERN ILL WOULD LIKELY HAVE THE
BETTER OPPORTUNITY FOR SOME PCPN...ALTHOUGH CHANCES APPEAR
SMALL...AS WOULD AMOUNTS.
.LONG TERM...MONDAY THROUGH THURSDAY
230 AM CDT FRI AUG 17 2012
OVERALL TREND FAVORS SHIFTING THE UPPER LEVEL TROUGH EASTWARD FOR
THE NEW WORK WEEK...WHILE THE RIDGE TO THE WEST WORKS TOWARD THE
REGION...BREAKING DOWN SOMEWHAT. 17.00Z GFS IN BETTER AGREEMENT WITH
THE EC AND GEM...HOLDING OFF ON WHAT WOULD HAVE BEEN A MID WEEK
SHORTWAVE. INSTEAD...ITS MORE SUGGESTIVE OF A BIT OF UPPER LEVEL
ENERGY MOVING ACROSS THE NORTHERN GREAT LAKES...DRAGGING A SFC
BOUNDARY ACROSS THE REGION. SMALL RAIN CHANCES COULD RESULT ON WED.
GFS TRENDS AWAY FROM THE EC THU-FRI...PUSHING A SHORTWAVE INTO THE
UPPER LEVEL RIDGE ABOUT A DAY FASTER THAN THE EC. THE THE GFS HAS
NOT SHOWN MUCH CONSISTENCY WITHIN ITSELF WHILE THE EC HAS BEEN
BETTER RUN TO RUN. OVERALL...CONFIDENCE NOT THAT HIGH BY MID/LATE
WEEK...AND WILL LEAN ON THE CONSENSUS/EC SOLUTION FOR NOW. WITH SOME
CHANGE TO A MORE ZONAL-RIDING A LOFT PATTERN...EXPECT TEMPS TO
GRADUALLY WARM BACK TO SEASONABLE NORMS.
&&
.AVIATION...THROUGH 18Z SATURDAY
1213 PM CDT FRI AUG 17 2012
THE MAIN CONCERN THROUGH SATURDAY MORNING IS WHETHER VALLEY FOG
WILL FORM AND RESTRICT THE VISIBILITY AT KLSE. THE 17.12Z NAM AND
17.15Z RAP CONTINUE TO SHOW SOME SIGNALS THAT THE VALLEY FOG IS
NOT A CERTAINTY TO FORM. WHILE THE SURFACE HIGH WILL BE OVER THE
AREA TO PROVIDE CLEAR SKIES AND LIGHT WINDS THROUGH A DEEP
LAYER...THE CONCERN IS WHETHER SATURATION WILL OCCUR. DEW POINTS
THIS AFTERNOON ARE EXPECTED TO MIX OUT INTO THE LOWER TO MIDDLE
40S AND THEN RECOVER AROUND 5 DEGREES DURING THE EVENING. NEITHER
THE NAM OR THE RAP SHOW ENOUGH RECOVERY IN THE DEW POINT OR
COOLING OF THE SURFACE TEMPERATURES TO ALLOW SATURATION TO OCCUR.
THE SHORT TERM LAV GUIDANCE WHICH IS USUALLY AGGRESSIVE WITH THE
FORMATION OF FOG AND VISIBILITY RESTRICTION ALSO DOES NOT SHOW ANY
FOG FORMING DESPITE ONLY HAVING A 1 TO 2 DEGREE TEMP/DEW POINT
SPREAD LATE TONIGHT. THUS WITH MIXED SIGNALS...HAVE NOT MADE ANY
CHANGES TO THE FORECAST FOR KLSE. STILL FEEL THERE WILL BE SOME
VALLEY FOG THAT FORMS...BUT WITH CONCERNS ON HOW MUCH...LEFT THE
VISIBILITY MVFR WITH THE INCLUSION OF BCFG. NO CONCERNS AT KRST
THROUGH 18Z SATURDAY WITH VFR CONDITIONS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
230 AM CDT FRI AUG 17 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...04
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
249 PM MDT FRI AUG 17 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...
WATER VAPOR IMAGERY SHOWS FAST NORTHWEST FLOW ALOFT OVER THE WY/MT
WITH A STRONG SHORTWAVE DIVING SOUTHWARD OVER SASKATCHEWAN.
CUMULUS HAVE DEVELOPED OVER THE LARAMIE RANGE BUT FAILED TO MOVE
EASTWARD OVER THE PLAINS. THE MODELS ARE IN AGREEMENT IN SHOWING
THE SHORTWAVE DIVING SSE OVER THE NORTHERN PLAINS THROUGH TONIGHT.
ALTHOUGH THERE IS LIMITED LOW AND MIDLEVEL MOISTURE TO WORK
WITH...THE QG LIFT AHEAD OF THE SHORTWAVE COULD ENHANCE
CONVECTIVE CHANCES LATE THIS AFTERNOON AND EVENING. CURRENT LAPS
ANALYSIS SHOWS WEAK SFC INSTABILITY OVER THE PLAINS (WITH A FEW
HUNDRED J/KG OF CAPE). BOTH THE GFS AND HRRR MODELS GENERATE
ISOLATED STORMS OVER THE SOUTHEASTERN PART OF THE CWA BETWEEN 00Z
AND 06Z. KEPT SLIGHT CHANCE POPS FOR MAINLY AREAS ALONG INTERSTATE
80 TO THE EAST OF THE LARAMIE RANGE THROUGH EARLY TONIGHT. A
1018MB SFC HIGH BEHIND THE SHORTWAVE WILL DRIVE A COLD FRONT
THROUGH THE AREA LATE TONIGHT. BREEZY CONDITIONS WILL DEVELOP SAT
MORNING AFTER THE FROPA...HOWEVER PRESSURE RISES/SOUNDINGS DO NOT
SUGGEST THAT THE WINDS WILL BE PARTICULARLY STRONG.
RATHER QUIET THROUGH THE REMAINDER OF THE SHORT TERM WITH VERY DRY
NORTHWESTERLY FLOW ALOFT. HIGHS ON SAT WILL BE AROUND 5 DEGREES
COOLER IN THE POST FRONTAL AIRMASS. THE BREEZY NORTHERLY WINDS
WILL SUBSIDE ON SAT NIGHT AS THE SFC HIGH PRESSURE CENTER SETTLES
OVER THE CWA. WENT A FEW DEGREES COOLER THAN MOS FOR LOWS ON SAT
NIGHT...WITH VALUES MAINLY IN THE MID-TO-UPPER 40S OVER THE
PLAINS...WITH GOOD RADIATION AL COOLING POTENTIAL. 700MB TEMPS RISE
ON SUN TO 9C (FROM 7C ON SAT) FOR A FEW DEGREES OF WARMING...BUT
LITTLE OTHER CHANGE IN THE SENSIBLE WEATHER. A SHORTWAVE WILL
ROUND THE TOP OF THE INTERMOUNTAIN WEST RIDGE ON SUN
NIGHT...APPROACHING THE CWA BY MON.
.LONG TERM...MONDAY THROUGH FRIDAY
LONG TERM GENERALLY DOMINATED BY A RIDGE OF HIGH PRESSURE WITH
THE RIDGE AXIS WEST OF THE CWA EARLY. WE GET A SHORTWAVE THAT
MOVES DOWN THROUGH THE NORTHWEST FLOW MONDAY...EXITING EAST BY
MONDAY AFTERNOON. GENERALLY DRY CONDITIONS EXPECTED WITH THE
EXCEPTION POSSIBLY BEING THE HIGHER TERRAIN OF THE SNOWY...SIERRA
MADRE AND NORTHERN LARAMIE RANGES MONDAY AFTERNOON.
RIDGE AXIS THEN BUILDS OVER THE CWA TUESDAY WITH THE AXIS SHIFTING
EAST BY TUESDAY AFTERNOON. COULD SEE AN INCREASE IN FIRE WEATHER
CONCERNS AS WINDS SHIFT SOUTHWEST AND BEGIN TO INCREASE. GFS
SHOWING 20 TO 25KTS OF WIND AT 700MB AS ANOTHER SHORTWAVE TRACKS
INTO IDAHO AND NORTHERN UTAH. THIS SHORTWAVE TRACKS NORTHEAST
ACROSS WESTERN WYOMING TUESDAY NIGHT INTO WEDNESDAY...DRAGGING A
COLD FRONT THROUGH AT LEAST OUR WESTERN ZONES WEDNESDAY EVENING.
MAINTAINED...AND SLIGHTLY INCREASED POP COVERAGE FOR THIS AREA
WEDNESDAY NIGHT. WEDNESDAY MOST LIKELY OUR WARMEST DAY NEXT WEEK
WITH HIGHS CLIMBING BACK INTO THE 90S WITH THESE GUSTY WINDS. DRIER
CONDITIONS RETURNING FOR THE END OF THE WEEK CWA WIDE.
&&
.AVIATION...18Z TAFS
VFR CONDITIONS EXPECTED NEXT 24 HOURS AT MOST AIRPORTS ACROSS
SOUTHEAST WYOMING AND NEBRASKA PANHANDLE. CHEYENNE COULD SEE SOME
ISOLATED THUNDERSTORMS THIS AFTERNOON...BUT CONFIDENCE NOT HIGH
ENOUGH TO NAIL DOWN TIMING. WENT WITH VCTS WORDING IN TAF UNTIL THE
01-02Z TIME FRAME. ELSEWHERE...MAINLY CLEAR SKIES AND NO IMPACTS TO
AVIATION INTERESTS.
&&
.FIRE WEATHER...
FIRE WEATHER CONCERNS WILL BE MINIMAL THROUGH THE WEEKEND. A COLD
FRONT WILL MOVE ACROSS THE AREA TONIGHT BRINGING BREEZY NORTHERLY
WINDS AND COOLER THAN AVERAGE TEMPERATURES ON SATURDAY. MINIMUM
AFTERNOON RELATIVE HUMIDITY VALUES WILL BE IN THE 15 TO 20 PERCENT
RANGE. THE AIRMASS WILL BEGIN TO WARM ON SUNDAY WITH AFTERNOON
HUMIDITIES DROPPING BELOW 15 PERCENT TO THE WEST OF THE LARAMIE
RANGE. HOWEVER...WINDS WILL BE LIGHT WITH THE SURFACE HIGH
PRESSURE CENTER NEAR SOUTHEAST WYOMING. PRECIPITATION CHANCES WILL
BE LOW THROUGH EARLY NEXT WEEK WITH A DRY AIRMASS IN
PLACE...HOWEVER SOME ISOLATED SHOWER AND THUNDERSTORMS WILL BE
POSSIBLE STARTING MONDAY OVER THE MOUNTAINS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...FINCH
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1120 PM MDT THU AUG 16 2012
.AVIATION...06Z TAFS...
VFR EXPECTED OVER ALL TERMINALS THROUGH FRIDAY NIGHT UNDER NW FLOW
ALOFT. AND SFC HIGH OVER THE CENTRAL PLAINS INTO THE MIDWEST. -RE-
&&
.PREV DISCUSSION... /ISSUED 835 PM MDT THU AUG 16 2012/
.UPDATE...
REMOVED SLIGHT CHANCE POPS AND DECREASED CLOUD COVER FOR THE
OVERNIGHT PERIOD ACROSS THE SOUTHERN PART OF THE CWA. THE 18Z GFS
WAS THE MOST BULLISH IN INCREASING LLVL RH/LOW CLOUDS ALONG
INTERSTATE 80 OVER THE PLAINS...HOWEVER THE GFS SFC DEWPOINTS WERE
AROUND 5 DEGREES TOO HIGH AT 00Z. THUS...TENDED TO SIDE WITH THE NAM
AND HRRR MODEL OUTPUT THAT SHOWED LIMITED LOW CLOUD DEVELOPMENT
OVERNIGHT.
&&
PREV DISCUSSION... /ISSUED 338 PM MDT THU AUG 16 2012/
SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT...
WIDESPREAD STRATUS HAS BEEN SLOW TO ERODE THIS AFTN OWING TO
PERSISTENT LOW-LEVEL UPSLOPE FLOW...AND A MUCH DEEPER CLOUD LAYER
THAN PREVIOUSLY THOUGHT GIVEN EARLIER RETURNS FROM THE CYS VAD
WIND PROFILE. WINDS HAVE FINALLY SHIFTED TO THE S ACROSS MUCH OF
THE AREA...MINIMIZING THE UPSLOPE COMPONENT AND ALLOWING CLOUD
COVER TO RAPIDLY DIMINISH ACROSS SOUTHEAST WY AND THE WESTERN NE
PANHANDLE. TEMPERATURES HAVE RESPONDED NICELY WHERE SIGNIFICANT
CLOUD BREAKS HAVE BEEN NOTED ON RECENT VISIBLE SATELLITE IMAGERY
WITH SOUTHEAST WYOMING SEEING TEMPERATURES CLIMB INTO THE MIDDLE
TO UPPER 60S. THE RESULTANT DESTABILIZATION WITH SLIGHTLY NEGATIVE
LIFTED INDEX VALUES...ALONG WITH LOW-LEVEL CONVERGENCE ALONG A
WEAK SURFACE TROUGH HAVE CONTRIBUTED TO SHOWER AND TSTM
DEVELOPMENT OVER THE COLORADO FRONT RANGE. THIS ACTIVITY SHOULD
SPREAD N INTO THE SNOWY AND SIERRA MADRE RANGES DURING THE LATE
AFTN AND EARLY EVE.
ACTIVE NORTHWEST FLOW ALOFT SHOULD CONTINUE INTO THE OVERNIGHT
GIVEN RECENT TRENDS IN WATER VAPOR SATELLITE IMAGERY. MULTIPLE
SHORTWAVE DISTURBANCES APPEAR TO BE EMBEDDED WITHIN THE FLOW AND
COULD AFFECT THE AREA LATER TONIGHT. MODEL GUIDANCE SUGGESTS THE
STRONGEST SUCH WAVE WILL TRACK ACROSS EAST CENTRAL WY INTO THE
NORTHERN NE PANHANDLE BETWEEN 6Z AND 12Z FRI. WEAK PVA AND 700
MILLIBAR THETA E ADVECTION IN ADVANCE OF THIS WAVE COULD HELP TO
INITIATE A FEW LIGHT RAIN SHOWERS...BUT ACTIVITY SHOULD REMAIN
QUITE ISOLATED GIVEN LIMITED MOISTURE. LINGERING CLOUD COVER MAY
LIMIT RADIATIONAL COOLING TO SOME EXTENT...WHICH COULD KEEP
TEMPERATURES UP A FEW DEGREES THROUGH TONIGHT.
MOISTURE BEGINS TO INCREASE ON FRI OVER THE WESTERN NE PANHANDLE
IN ADVANCE OF A WEAK SFC TROUGH. CONVERGENCE ALONG THIS BOUNDARY
DOES NOT APPEAR TO BE TOO IMPRESSIVE...AND MUCH OF THE AREA WILL
REMAIN IN THE SUBSIDENCE OF AN UPPER-LEVEL JET STREAK MOVING TO
THE N. DESPITE THE POTENTIAL FOR MODEST DESTABILIZATION WITH UPPER
40S AND LOWER 50S BOUNDARY LAYER DEW POINTS CONTRIBUTING TO A FEW
HUNDRED J/KG OF SBCAPE...THE RELATIVELY DRY WEATHER PATTERN AND
LIMITED DYNAMICS SUGGEST DRY CONDITIONS WILL PREVAIL ON FRIDAY
AFTN AND EVE. FEWER CLOUDS AND H7 TEMPERATURES AROUND 10C SUGGEST
AFTERNOON HIGHS MAY ONCE AGAIN TOP 80 DEGREES OVER THE HIGH PLAINS
OF SOUTHEAST WY. BEYOND FRIDAY...THE ADVANCEMENT OF DRY AIR IN THE
700 TO 300 MB LAYER ON THE EASTERN PERIPHERY OF A BUILDING UPPER-
LEVEL RIDGE OVER THE WESTERN CONUS WILL KEEP THINGS DRY THROUGH
THE REMAINDER OF THE PERIOD.
LONG TERM...SUNDAY THROUGH WEDNESDAY...
DRY AND MILD WILL BE THE MAIN STORY THROUGH THE LONG TERM
PERIOD. SUNDAY WILL START OFF UNDER DRY NORTHWEST FLOW ALOFT
WITH AN UPPER RIDGE OVER THE INTERMOUNTAIN WEST. A FEW WEAK
DISTURBANCES MAY MOVE THROUGH NORTHWEST FLOW EARLY IN THE EXTENDED
PERIOD BUT DISTURBANCES SHOULD BE WEAK AND TIMING IS UNCERTAIN.
CHANCES FOR PRECIPITATION IN THE PLAINS IS VERY LOW BUT SHOULD SEE
AT LEAST A FEW SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS. RIDGE
AXIS TO SHIFT ACROSS THE NORTHERN ROCKIES BY MID WEEK KEEPING MOST
OF THE FORECAST AREA DRY BUT EXTENDED MODELS DO INDICATE A PACIFIC
SHORTWAVE MOVING THROUGH THE RIDGE. TIMING AND PLACEMENT HAVE BEEN
INCONSISTENT BETWEEN MODEL RUNS AND THE GFS AND EC SOLUTIONS NOT IN
AGREEMENT. MOST LIKELY CHANCES FOR PRECIPITATION WILL HOLD OFF UNTIL
LATE NEXT WEEK...ASSUMING SHORTWAVE TRACK IS FAR ENOUGH SOUTH TO
IMPACT THE FORECAST AREA.
FIRE WEATHER...
A COOLER AND MORE HUMID WEATHER PATTERN WILL PRECLUDE ANY NOTABLE
FIRE WEATHER CONCERNS THROUGH TONIGHT. WARMER AND DRIER CONDITIONS
WILL RETURN TO THE REGION ON FRIDAY THROUGH SUNDAY BENEATH A RIDGE
OF HIGH PRESSURE...WITH DAYTIME HIGH TEMPERATURES IN THE UPPER 70S
AND LOWER 80S OVER THE LOWER ELEVATIONS. AFTERNOON RELATIVE
HUMIDITY VALUES COULD BE AS LOW AS 13 TO 17 PERCENT ON FRIDAY AND
SATURDAY OVER THE LOWER ELEVATIONS OF CARBON COUNTY AND PORTIONS
OF THE SOUTHERN NEBRASKA PANHANDLE. GUSTY NORTH TO NORTHEAST WINDS
AT 15 TO 20 MPH COULD COMBINE WITH LOW RELATIVE HUMIDITY TO CREATE
NEAR CRITICAL FIRE WEATHER CONDITIONS OVER THE SOUTHERN PANHANDLE
ON SATURDAY AFTERNOON. WARM AND DRY CONDITIONS WILL CONTINUE
THROUGH NEXT WEEK WITH ONLY VERY SMALL CHANCES FOR SHOWERS AND
THUNDERSTORMS OVER THE MOUNTAINS. MINIMUM RELATIVE HUMIDITY VALUES
WILL BE IN THE MIDDLE TEENS EACH DAY THROUGH FRIDAY...BUT WINDS
SHOULD BE LIGHT.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...FINCH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
143 AM EDT Sun Aug 19 2012
.NEAR TERM [through Tonight]...
The PoP forecast is tricky tonight as most of the guidance does not
appear to have a very good handle on the large mass of rain with
embedded thunderstorms approaching from the west. The 18z NAM does
not know that this rain exists, and most of the hi-res guidance is
struggling as well. The HRRR seems to have a fair handle on the
current rain area though and moves it eastward overnight while
gradually weakening. Although gradual weakening is expected, it will
likely move into at least the western part of the forecast area
overnight, so PoPs were raised into the likely range (60-70 percent)
roughly from the Apalachicola river westward, with 30-50 percent
PoPs east of there. This is only round 1 of what may be several
rounds of showers with embedded thunderstorms over the next few days
with a tropical airmass in place and the base of a broad upper level
trough affecting the area.
$$
.SHORT TERM [Sunday through Monday Night]...
Looks like a very unsettled period with the broad trough over the
eastern CONUS deepening as several impulses drop southeastward from
the plains into the base of the trough. The axis of the trough will
remain west of the local region which will tap into the tropical
moisture associated with Helene or its remnants in the deep layer
southwest flow. The GFS continues to show the upper jet dipping well
into the southeastern states Sunday into Monday placing the
Tri-State area within the right entrance region. SPC`s day 2
discussion currently mentions this put no highlighted area for a
severe risk at this time. This will need to be monitored closely. At
the surface, a cold front will approach from the northwest pushing
into our western zones Monday possibly becoming quasi-stationary late
Monday or Tuesday. As mentioned in an earlier discussion, this could
set the stage for a heavy rain event with localized flooding.
Understandably PoPs will be rather high during this period and will
generally go above numerical guidance. Max temps will be held down a
few degrees with the extensive cloud cover and convective activity.
&&
.LONG TERM [Tuesday through Saturday]...
With the mean upper level trough expected to remain quite persistent
across the eastern half of the U.S. through much (if not all) of the
upcoming week, impulses of energy rounding the base of the trough
over the Southeast will combine with plenty of deep layer moisture
to keep above normal PoPs in the fcst throughout much of the
extended period. Additionally, the likely remnants of Tropical Storm
Helene (which is still progged to move into southern Mexico, well
away from our region), may still play an important role in our fcst
before the week is over. While there are still plenty of
discrepancies between the global models (and run to run differences
within each model) over timing and potential moisture influx, the
simple presence of the steep upper level trough, will likely pull in
some deep layer tropical moisture into our region from the SW by mid
to late next week. Now, the latest runs of the GFS (00 UTC) and ECMWF
(12 UTC Thu), are back to showing some potential for a "break" in
the organized convection later on Tue. and possibly lasting into
Thu., but am not ready to buy into this solution just yet, given the
numerous changes and uncertainty surrounding Helene. Should this
become a trend that all of the global models begin embracing, then
PoPs can be adjusted downward at a later time. Also, with the
increased cloud cover which is still expected during the day, the
effects of the more typical afternoon sea breeze will be somewhat
limited (except for possibly Tue aftn thru Thu.), so high temps
should average a bit below climo values through much of the period.
While this does NOT appear to be the best stretch of "beach weather"
by any means, the potential of a good stretch of widespread rainfall
will certainly help many areas to continue to chip away at our long
term ongoing drought. Please stay tuned to the latest fcsts from the
National Weather Service, as this pattern may need some fine tuning
once the global models come into better agreement with each other,
and maintain more run to run consistency.
&&
.AVIATION [through 06z Monday]...
Updated at: 140am
Confidence is low for this set of TAFs as there is a fair amount of
disagreement amongst the models as to how SHRA and TS will evolve
today. For now, we went with the idea of MVFR CIGS developing late
tonight and lingering into the morning hours, with VFR thereafter.
As far as timing of SHRA and TS, we went with the general idea of
rapid development in the 09-12z timeframe - beginning at the Gulf
coast and then spreading inland. Although there is disagreement on
location and timing of convection for much of the day, models do
seem to agree on an early start to things. Some MVFR/IFR is likely
to exist in and near SHRA and TS for the bulk of the day. However,
confidence in continued activity beyond about 18z is low, so that
time frame was kept VFR across the board for now at terminals.
&&
.MARINE...
Winds will be from the southwest at least through mid-week with
winds and seas gradually increasing to cautionary levels by Tuesday
as the pressure gradient tightens ahead of a cold front. This front
will also bring numerous showers and thunderstorms to the coastal
waters. Winds and seas may subside below headline criteria on
Wednesday.
&&
.FIRE WEATHER...
Typical of this wet summer pattern, afternoon relative humidities
will remain well above critical levels over the next several days
and, and therefore, conditions will continue to remain safely
above red flag levels.
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...DVD
SHORT TERM...Barry
LONG TERM...Gould
AVIATION...Lamers
MARINE...Barry
FIRE WX...Block
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
215 AM EDT SUN AUG 19 2012
.UPDATE...
NO SIGNIFICANT CHANGES SO FAR BUT PLANNING ON UPPING POPS OVERNIGHT.
RECENT HRRR RUNS AND 12Z AND 18Z GFS REALLY UPPING POTENTIAL FOR
OVERNIGHT SHRA/TSRA. HRRR TIMING ONSET AT ATL METRO ABOUT 06Z WITH
GFS A LITTLE LATER. OTHER MODELS INCLUDING LOCAL 4KM WRF AND NCEP
4KM WRF NMM NOT SO OPTIMISTIC ABOUT PRECIP. BEST H8 WAA ON GFS
PROGGED MORE OVER MIDDLE GA WITH SOME WAA AT HIGHER LEVELS FURTHER
NORTH.
SNELSON
&&
.PREV DISCUSSION... /ISSUED 321 PM EDT SAT AUG 18 2012/
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
EXPECT AN ACTIVE WEATHER PATTERN THROUGH THE SHORT TERM. SURFACE
ANALYSIS SHOWS A COLD FRONT NEAR A CARROLLTON TO ATLANTA TO ATHENS
LINE. EXPECT A STRONG UPPER DISTURBANCE OVER MS TO TRAVERSE THE AREA
AND SPARK ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND
SOUTH OF THE FRONT THROUGH MID EVENING. THIS ACTIVITY SHOULD
DIMINISH BY MIDNIGHT... BUT THE BREAK MAY BE SHORT LIVED AS A SERIES
OF DISTURBANCES BEGIN TO CARVE A LONG WAVE TROUGH ALONG THE LOWER MS
VALLEY REGION OVERNIGHT AND ON SUNDAY. AS A RESULT... EXPECT A VERY
ACTIVE SW FLOW ALOFT TO INTERACT WITH AN INCREASINGLY MOIST AND
UNSTABLE AIRMASS TO SPARK SCATTERED TO WIDESPREAD CONVECTION ACROSS
MUCH OF THE AREA STARTING EARLY ON SUNDAY AND CONTINUING THROUGH
MONDAY. THE GFS SHOWS A SURFACE LOW DEVELOPING ALONG THE STALLED
FRONT AND SWEEPING ACROSS THE STATE MONDAY NIGHT... WITH THE
TRAILING COLD FRONT FINALLY BRINGING SOME DRIER CONDITIONS TO AT
LEAST NORTH GA BY TUESDAY MORNING. AT THIS TIME...EXPECT THE
STRONGER STORMS TO OCCUR ON MONDAY AS THE UPPER TROUGH DEEPENS AND A
SURFACE LOW PUSHES INTO THE STATE DURING DAYTIME HEATING.
ALTHOUGH AMPLE CLOUD COVER AND WIDESPREAD SHOWERS SHOULD HELP
HINDER SEVERE STORM DEVELOPMENT ON SUNDAY AND MONDAY... THE
INCREASED FORCING EXPECTED ON MONDAY WARRANTS GREATER CONCERN FOR
MONDAY AFTERNOON AND EVENING. SPC DOES NOT HAVE THE FORECAST AREA
OUTLOOKED AT THIS TIME... BUT WILL MONITOR THIS POTENTIAL CLOSELY
GOING INTO MONDAY. OTHERWISE...LEANED TOWARD A MAV AND MET BLEND
FOR LOWS AND HIGHS THROUGH THE PERIOD WITH SOME UNCERTAINTY ON
TIMING AND COVERAGE OF CONVECTION AT THIS TIME.
39
LONG TERM /TUESDAY THROUGH SATURDAY/...
OVERALL GUIDANCE IN BETTER AGREEMENT THAN YESTERDAY WITH MAIN
INFLUENCING FEATURES FOR THE MAJORITY OF THE LONG TERM. THROUGH
TUESDAY BOTH THE GFS AND ECMWF KEEP THE MOISTURE FIELD SOUTH OF THE
NEARLY STATIONARY SFC FRONT ACROSS CENTRAL GEORGIA...WHICH
EVENTUALLY SAGS ACROSS SOUTHERN GEORGIA FOR WEDNESDAY INTO THURSDAY.
CURRENT POPS OF LOW END CHANCE IN THE SOUTH TO SLIGHT NORTHWARD
THROUGH THIS PERIOD SEEM REASONABLE. THE ECMWF HINTS AT A WEAK UPPER
LOW DRAWING MOISTURE IN A BIT FARTHER NORTHWARD THAN THE GFS ON
THURSDAY... BUT THERE IS DECENT UNCERTAINTY IN THIS SOLUTION THIS
FAR OUT SO WILL KEEP BEST CHANCE POPS IN SOUTH AND EAST PORTIONS.
WEAK SFC HIGH BUILDING INTO AREA NEAR END OF THE WEEK SHOULD LIMIT
CONVECTIVE DEVELOPMENT SO WILL ALSO CONTINUE THE CURRENT SLIGHT POPS
FOR THAT TIMEFRAME. NO SIGNIFICANT CHANGES NEEDED TO THE FORECAST
TEMPS AS LATEST MEX GUIDANCE KEEPING BETTER CONSISTENCY BETWEEN RUNS
THAN YESTERDAY. WITH ALL CONSIDERED...FORECAST LOOKS TO BE ON TRACK.
PREVIOUS DISCUSSION FOLLOWS...
03
PREVIOUS DISCUSSION ISSUED AT 426 AM EDT SAT AUG 18 2012/...
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
CWA REMAINS UNDER THE INFLUENCE OF A LONGWAVE TROUGH AT THE
BEGINNING OF THE LONG TERM. LATEST GUIDANCE STILL BRINGS A WAVE
ACROSS THE CWA NEAR THE BEGINNING OF THE LONG TERM BUT ABOUT 12
HOURS EARLIER THAN SUGGESTED YESTERDAY WITH MODELS SHOWING SUNDAY
NIGHT NOW. ALTHOUGH NAM/GFS/ECMWF/SREF SHOW SOME REFLECTION OF A
SFC LOW ASSOCIATED WITH THIS DISTURBANCE...THE GFS IS BY FAR THE
STRONGEST AND APPEARS TO BE OVERDONE ON STRENGTH AND PRECIP. AT
LEAST THROUGH MONDAY...LEANED TOWARD THE NAM/ECMWF SOLUTION TO
ACCOUNT FOR THE OVERDONE GFS. MAIN IMPACT WAS TO POPS THAT ARE IN
THE SLIGHT CHANCE TO LIKELY CATEGORY THROUGH MONDAY AS OPPOSED TO
THE LIKELY AND CATEGORICAL POPS SUGGESTED BY THE GFS. AFTER THE
INFLUENCES FROM THE WAVE ON MONDAY MOVES OUT OF THE CWA...RAIN
CHANCES DECREASE. BEST MOISTURE REMAINS ACROSS SOUTHERN HALF OF
CWA SO HAVE CONTINUED TO SHOW BEST POPS ACROSS THAT AREA. BY
MIDWEEK...LONGWAVE TROUGH CONTINUES TO BREAK DOWN ACROSS THE AREA
AND BEST MOISTURE CONTINUES TO SHIFT OFF TO THE EAST AS HIGH
PRESSURE PUSHES INTO THE CWA AT THE SFC. THIS WILL HELP TO LIMIT
POPS TO SLIGHT CHANCE ACROSS THE NORTH AND CHANCE ACROSS THE
SOUTHERN HALF OF THE CWA.
MEX MAX TEMPS ARE SLIGHTLY HIGHER THAN PREVIOUS RUN. LIKE THIS TREND
AND HAVE EVEN NUDGED MAX TEMPS UP A DEGREE IN SOME PLACES. MIN TEMPS
APPEAR A LITTLE COOL DURING THE WORK WEEK...SO HAD TO MAKE SOME
ADJUSTMENTS UPWARD HERE TOO.
11
AVIATION...
06Z UPDATE...
MAINLY MVFR CIGS GENERALLY 020-030 SCT-BKN THROUGH 12Z...THEN VFR
REMAINDER OF PERIOD. VFR VSBYS OVER TAF SITES. A COLD FRONT REMAINS
NEARLY STATIONARY ACROSS THE ATLANTA METRO AREA... AND WITH AN
ACTIVE WESTERLY FLOW ALOFT. SHOWERS AND THUNDERSTORMS CONTINUE TO
DIMINISH...BUT BROAD AREA OF RAIN PERSIST INTO EASTERN ALABAMA.
MAINLY VFR CONDITIONS BEHIND PRECIP SHIELD. AS NEXT WAVE MOVES ALONG
FRONT...PROB30 FROM 18Z FOR MORE SHRA/TSRA...BUT VCSH FROM 12Z-18Z.
WINDS EXPECTED TO REMAIN WEST TO NORTHWEST UNDER 10KTS.
//ATL CONFIDENCE...
06Z UPDATE...
MODERATE CONFIDENCE ON CONVECTION AND TIMING. HIGH CONFIDENCE ON
ALL OTHER ELEMENTS.
37
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 68 86 68 84 / 30 50 60 60
ATLANTA 69 86 69 83 / 30 60 60 60
BLAIRSVILLE 62 80 66 80 / 20 30 50 50
CARTERSVILLE 68 85 67 84 / 30 50 60 60
COLUMBUS 72 87 70 84 / 30 60 70 70
GAINESVILLE 68 85 68 83 / 30 50 60 60
MACON 71 88 70 86 / 30 60 70 70
ROME 69 87 68 85 / 30 40 50 60
PEACHTREE CITY 68 86 67 84 / 30 60 60 60
VIDALIA 72 89 72 85 / 30 60 70 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
511 AM EDT SUN AUG 19 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 507 AM EDT SUN AUG 19 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP TROF DOMINATING THE
ERN CONUS. TROF CONTINUES TO BE ANCHORED BY A MID/UPPER LEVEL
CYCLONE CENTERED IN THE VCNTY OF JAMES BAY...AND THE UPPER LAKES ARE
FIRMLY UNDER THE INFLUENCE OF THE TROF. ALTHOUGH SHORTWAVE AND
ASSOCIATED COLD FRONT PASSED YESTERDAY AFTN/EVENING...VARYING
AMOUNTS OF CLOUD COVER LINGER OVER UPPER MI EARLY THIS MORNING. OCNL
CLOUD COVER IS PROBABLY PREVENTING A MORE WIDESPREAD OR DENSE FOG
FROM DEVELOPING AS SEVERAL SITES HAVE HAD WIDELY FLUCTUATING VIS
DURING THE NIGHT.
WITH UPPER MI REMAINING FIRMLY UNDER THE INFLUENCE OF THE MID/UPPER
TROF TODAY AND TONIGHT...MAIN FCST ISSUE IS WHETHER ANY PCPN WILL
OCCUR. IN SUMMERTIME NW FLOW...EVEN THE SUBTLEST OF WAVES CAN
TRIGGER ISOLD/SCT CONVECTION. WHILE THERE ARE NO OBVIOUS SHORTWAVES
EVIDENT UPSTREAM IN NRN ONTARIO...THERE ARE HINTS OF ONE JUST N OF
LAKE SUPERIOR THAT IS ANALYZED BY THE LATEST RUC. THAT SUBTLE WAVE
IS PROBABLY RESPONSIBLE FOR THE RECENT EXPANSION OF CLOUDS OVER THE
FCST AREA AS WELL AS THE ISOLD SHRA THAT HAVE DEVELOPED FROM
ONTONAGON COUNTY N TO JUST OFFSHORE OF THE KEWEENAW PENINSULA. ONE
ASPECT THAT WILL BE WORKING AGAINST CONVECTION TODAY WILL BE THE
DRIER AIR MASS EVIDENT UPSTREAM IN NRN ONTARIO PER 00Z CWPL
SOUNDING. AS AN INDICATION OF THE DRIER AIR...THE K INDEX WAS 3. A
NICE SWATH OF CLEAR SKIES WAS ALSO EVIDENT ACROSS NRN ONTARIO TO THE
NW OF LAKE SUPERIOR YESTERDAY AFTN...AND SFC DWPTS WERE DOWN INTO
THE 30S IN THAT AREA. HOWEVER...WITH AFORMENTIONED SUBTLE WAVE
DRIFTING S...DEVELOPMENT OF LAKE BREEZE CONVERGENCE ZONE BTWN LAKE
SUPERIOR AND LAKE MI AND WITH MODELS DELAYING ARRIVAL OF THE DRIER
AIR UPSTREAM...A MENTION OF AT LEAST ISOLD SHRA APPEARS WARRANTED
FROM ROUGHLY NEAR KIMT E TO S OF KERY IN THE LAKE BREEZE CONVERGENCE
ZONE THIS AFTN. WILL ALSO NEED TO MONITOR TRENDS OVER THE NEXT FEW
HRS TO SEE IF CURRENT EXPANDING CLOUD COVER IS A PRECURSOR TO
MORNING SHRA DEVELOPMENT OVER A LARGER PORTION OF THE FCST AREA.
ANY SHRA NEAR LAKE MI WILL END EARLY THIS EVENING AS SHORTWAVE SLIPS
TO THE S. OTHERWISE...IT SHOULD BE A DRY NIGHT THOUGH THERE ARE
HINTS THAT ANOTHER WAVE MAY BE DROPPING INTO THE AREA OVERNIGHT.
WILL BE SOMETHING TO MONITOR FOR POSSIBLY ADDING SLIGHT CHC/ISOLD
SHRA IN LATER FCSTS. POTENTIAL CLOUD COVER WITH WEAK WAVE MAKES FOR
A CHALLENGING MIN TEMP FCST TONIGHT. AT THIS TIME...IT APPEARS CLOUD
COVER SHOULD BE LIMITED ENOUGH FOR AT LEAST THE FIRST PART OF THE
NIGHT TO FAVOR THE LOWER END OF AVBL GUIDANCE. SOME UPPER 30S WILL
BE POSSIBLE IN TRADITIONAL INTERIOR COLD SPOTS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 507 AM EDT SUN AUG 19 2012
GENERAL AGREEMENT IS PRESENT IN OVERALL UPPER AIR PATTERN THROUGH
THE UPCOMING WEEK. DEEP TROUGH OVER MOST OF EASTERN CANADA INTO THE
EASTERN CONUS /INCLUDING GREAT LAKES/ DE-AMPLIFIES BY WEDNESDAY. BY
THE MID-LATE WEEK...TROUGH OVER WESTERN CANADA INTO PACIFIC NORTHWEST
EJECTS A PIECE OF ENERGY INTO THE NORTHERN PLAINS. WHERE THAT WEAKER
TROUGH PROGRESSES IS A QUESTION AND WILL HAVE IMPACT ON FORECAST OVER
UPPER GREAT LAKES THURSDAY AND FRIDAY. FAIR TO SAY THAT AGREEMENT
FROM THE GFS/ECMWF/GEM-NHEM IS BETTER TO START THE WEEK THAN TO END
THE WEEK. MAIN ISSUE AT END OF WEEK IS HOW FAR EAST ENERGY OVER THE
NORTHERN PLAINS WILL MOVE INTO THE GREAT LAKES. GFS CONTINUES TO BE
DEEPER AND FARTHER EAST...RESULTING IN GOOD CHANCE OF PRECIPITATION
ON FRIDAY OVER UPPER MICHIGAN. ECWMF/EXTRAPOLATION OF GEM-NHEM WOULD
KEEP MAJORITY OF FORCING AND PRECIPITATION WITH THE WEAKER TROUGH
SOUTHWEST OF UPPER MICHIGAN INTO THE UPPER MISSISSIPPI RIVER VALLEY.
TO START THE LONG TERM...HAVE A SMALL SHOT AT ISOLD SHRA ON MONDAY
OVER CENTRAL CWA IN THE MID-LATE AFTERNOON AS LAST OF STRONGER
SHORTWAVES DROP SOUTH ON WESTERN PERIFERY OF LARGER SCALE UPPER
TROUGH. FORECAST SOUNDINGS FROM GFS AND NAM INDICATE MOISTURE OVER
THE CWA ONLY FOCUSES BETWEEN 800MB AND 700MB. DRY AIR BELOW LCL
IS QUITE DRY AS DAY BEGINS WITH DEWPOINTS IN THE 30S. PROBABLY WILL
ONLY SEE DEWPOINTS RISE INTO THE MID 40S AT BEST IN THE AFTERNOON AS
LOW-LEVEL MOISTURE ADVECTION IS LIMITED. SREF IDEA SHOWING QPF
FORMING OVER SCNTRL CWA AFTER 18Z IS LIKELY ON TRACK. COVERAGE OF ANY
SHRA WILL BE VERY ISOLATED DUE TO DRY LOW-LEVELS. NO TSRA INCLUDED
WITH POOR MID-LEVEL LAPSE RATES LESS THAN 6C/KM AND SBCAPE VALUES
ONLY UP TO 200 J/KG. MODELS HINT AT MID-LEVEL MOISTURE STICKING
AROUND OFF AND ON THROUGH MONDAY NIGHT BUT WITH SAME LIMITING FACTORS
AS MONDAY AFTERNOON DO NOT EXPECT MUCH IN WAY OF PRECIPITATION ON
MONDAY NIGHT.
COUPLE OF WEAKER SHORTWAVES RIPPLE THROUGH UPPER GREAT LAKES TUESDAY
BUT MOISTURE IS FORECAST TO BE EVEN SHALLOWER THAN ON MONDAY...AGAIN
CENTERED AROUND 800MB. ADDITIONAL MID-LEVEL MOISTURE COULD ROLL
ACROSS WITH SCT-BKN CLOUDS 15-20 KFT POSSIBLE. MIX OF CLOUDS AND
SUNSHINE GIVES WAY TO MORE SUNSHINE IN THE AFTERNOON...SO BASED ON
H85 TEMPS TOWARD AOA 12C EXPECT MAX TEMPS WELL INTO THE 70S FOR MOST
AREAS WITH EVEN A POTENTIAL OF SEEING SOME READINGS AROUND 80
DEGREES OVER WESTERN AND CENTRAL CWA.
LOOKING WELL TO THE NORTHWEST CURRENTLY THERE IS A PRETTY STRONG
SHORTWAVE CRESTING RIDGE OVER WESTERN CONUS INTO WESTERN CANADA.
WAVES IS OVER THE NORTHWEST TERRITORIES OF CANADA. MODELS SHOW WAVE
SPLITTING BUT ONE FORMIDABLE PIECE OF SHORTWAVE ENERGY IS FORECAST
TO DIG INTO NORTHWEST ONTARIO TUESDAY NIGHT INTO WEDNESDAY. GFS
FARTHER SOUTH WITH THE WAVE AND ASSOCIATED PRECIPITATION...BUT
ECMWF AND GEM-NHEM HAVE THE WAVE AS WELL...BUT NOT AS FAR SOUTH. NAM
APPEARS TOO FAST/WEAK WITH THE SHORTWAVE AND IS NOT PREFERRED. ALL
THE MODELS INDICATE AREA OF H85 TEMP AND H85-H7 MOISTURE ADVECTION
SETS UP JUST AHEAD OF THE WAVE AS IT DIGS TOWARD UPPER GREAT LAKES
TUESDAY NIGHT. USING BLEND OF LAST FEW GFS MODEL RUNS ALONG WITH
ECMWF/GEM-NHEM AND EVEN SOME OF THE SREF...KEPT POPS HIGHEST ON
TUESDAY NIGHT OVER NORTHERN SECTIONS OF LK SUPERIOR...AND NO REAL
POPS OVER LAND AREA OF UPPER MICHIGAN...ASIDE FROM ISLE ROYALE.
IDEA FITS SYNOPTIC PATTERN AS MOST LAND CWA WILL BE THE WITHIN THE
MORE UNFAVORABLE RIGHT EXIT REGION OF JET STREAK FOR PRECIPITATION.
KEPT SLIGHT CHANCES FOR WEDNESDAY OVER CENTRAL AND EAST AS LARGER
SCALE FORCING ALONG WITH WEAK SFC TROUGH COULD COMBINE WITH DAYTIME
HEATING TO HELP FORM SOME SHOWERS DURING THE PEAK HEATING OF THE DAY.
IN THE EXTENDED...00Z MODEL RUNS PROVIDE NO TRENDS OF NOTE ON EXTENT
OF LARGER SCALE TROUGHING OVER UPPER GREAT LAKES TO CLOSE THE WEEK.
GFS CONTINUES TO SHOVE UPPER TROUGH PUSHING INTO THE NORTHERN PLAINS
ON THURSDAY ON INTO THE UPPER GREAT LAKES ON FRIDAY. THE TROUGH ALONG
WITH INCREASING LOW-LEVEL MOISTURE ADVECTION AND PRESENCE OF SFC WARM
FRONT HELPS TO GENERATE PLENTY OF QPF FRIDAY INTO FRIDAY NIGHT. ON
THE FLIP SIDE THE LATEST ECMWF IS MORE SHUNTED TO THE SOUTHWEST WITH
THE UPPER TROUGH AND THUS BRINGS VERY LITTLE QPF INTO THE UPPER GREAT
LAKES WITH HIGH PRESSURE STAYING THE DOMINANT FEATURE. MAIN WARM
FRONT REMAINS WELL TO THE SOUTH OF CWA. LATEST CANADIAN LOOKS MORE
LIKE THE ECMWF BUT DOES TRY TO BRING SOME QPF INTO AT LEAST WESTERN
CWA ON FRIDAY. MODEL CONSENSUS INDICATES HIGHEST CHANCES FOR
PRECIPITATION FRIDAY INTO FRIDAY NIGHT...BUT THIS IS BEING BIASED
SOMEWHAT BY GFS MODEL ELEMENTS. WILL STAY WITH CONSENSUS GIVEN THE
STARK DIFFERENCES OFFERED UP BY ECMWF AND GFS...BUT CERTAINLY
POSSIBLE THAT FRIDAY MAY END UP MAINLY DRY COMPARED TO THE HIGHER
CHANCE POPS IN THIS FORECAST. DOES APPEAR THAT NEXT WEEKEND WOULD
FEATURE A DRYING TREND AS THE UPPER TROUGH DEPARTS THE AREA. TOUGH TO
GET TOO SPECIFIC ABOUT THOSE DETAILS THOUGH DUE TO THE MODEL
DIFFERENCES STILL AROUND LEADING INTO NEXT WEEKEND. TEMPERATURES
SHOULD SHOW WARMING TREND INTO NEXT WEEKEND AS H85 TEMPS STEADILY
CLIMB FROM WEDNESDAY TO SATURDAY. IF GFS IS CORRECT THOUGH...WARMING
WOULD BE TEMPERED THURSDAY AND DEFINITELY INTO FRIDAY WITH MORE
CLOUDS AND PRECIPITATION. &&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 137 AM EDT SUN AUG 19 2012
AREAS OF FOG CONTINUE TO PLAGUE PORTIONS OF UPPER MICHIGAN ALTHOUGH
DRIER AIR IS ATTEMPTING TO MOVE INTO THE REGION FROM THE NORTH.
SATELLITE IMAGERY SHOWS NARROW SLOT OF CLEAR SKIES PUSHING INTO THE
AREA WITH AN AREA OF MID CLOUDS RIGHT BEHIND THIS FEATURE. CLEARING
SKIES AND SUBSIDENCE SUPPORTS PATCHY FOG DEVELOPMENT IN THOSE AREAS
THAT RECEIVED DECENT AMOUNTS OF RAINFALL. LESS ANTECEDENT MOISTURE
AT KCMX SUGGESTS FOG WILL NOT BE AS PREVALENT THERE. TAF FORECASTS
TO BE VERY TRICKY AT KIWD AND KSAW AS VIS AND CIGS WILL VARY
SIGNIFICANTLY FOR SOME TIME. ONCE THE INVERSION STRENGTHENS...MVFR
AND OCCASIONAL IFR CIGS/VIS TO PREVAIL. AS HIGH PRESSURE BUILDS INTO
THE AREA IN EARNEST...VFR CONDITIONS WILL THEN PREVAIL THROUGH THE
REMAINDER OF THE FORECAST.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 507 AM EDT SUN AUG 19 2012
BRIEFLY TIGHTER PRESSURE GRADIENT WILL ALLOW NORTHWEST WIND GUSTS
TO REACH 20-25 KTS OVER EASTERN SECTIONS OF LK SUPERIOR THIS
AFTERNOON INTO THIS EVENING. WINDS DIMINISH OVERNIGHT TONIGHT AND
REMAIN MAINLY BELOW 20 KTS THROUGH WEDNESDAY AS HIGH PRESSURE STAYS
CLOSE BY. EXCEPTION COULD BE TUESDAY AFTERNOON AND EVENING OVER
WESTERN SECTIONS WITH SOUTHWEST WIND GUSTS PUSHING ABOVE 20 KTS IN
THE VICINITY OF ISLE ROYALE. LOW PRESSURE SYSTEM APPROACHING LATE
THIS WEEK RESULTS IN WINDS BECOMING MORE EAST TO SOUTHEAST AND
INCREASING OVER 20 KTS. WINDS MAY END UP HIGHER DEPENDING ON
ULTIMATE TRACK AND STRENGTH OF SURFACE LOW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...RJT
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 AM EDT SUN AUG 19 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 359 PM EDT SAT AUG 18 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER
ERN NAMERICA CENTERED AROUND CUTOFF UPR LO NEAR JAMES BAY. THERE ARE
SEVERAL SHRTWVS ROTATING THRU THE TROF AND ARND THIS FEATURE. THE
FIRST IS SETTLING S THRU ONTARIO WHILE ANOTHER NEAR LK WINNIPEG IS
DIVING SSEWD TOWARD NW MN. AT 15Z...THESE SHRTWVS/ACCOMPANYING SFC
TROF OVER LK SUP WITH SHARP WSHFT WERE SUPPORTING A BKN LINE OF SHRA
EXTENDING FM ERN LK SUP ACRS THE KEWEENAW THRU NRN MN TOWARD LK
WINNIPEG. THE 12Z INL RAOB SHOWS ABUNDANT MID LVL MSTR ABV A DRIER
SUB H75 LYR...AND THIS LOWER LVL DRY AIR SEEMS TO BE THE BIGGEST
IMPEDIMENT TO MORE WDSPRD SHRA. THE DRY AIR IS DEEPER TO THE S AS
INDICATED BY THE 12Z GRB RAOB...AND THE MRNG WAS MOSUNNY OVER THE
SCNTRL. TO THE N...MUCH DRIER LLVL AIR IS PRESENT ON THE 12Z YPL
RAOB UNDER HI PRES RDG AXIS EXTENDING SEWD INTO NW ONTARIO FM HI
PRES CENTERED OVER NRN MANITOBA. MODIFIED
LATE THIS AFTN...WITH ARRIVAL OF SFC TROF/ENHANCED LLVL CNVGC
ASSOCIATED WITH SHARP SYNOPTIC WSHFT THAT WL BE ENHANCED BY
BREEZE OFF LK SUP DURING PEAK HEATING TIME...THE SHRA HAVE BECOME
MORE NMRS WITH SOME EMBEDDED TS ON A LINE THRU THE CNTRL ZNS.
MODIFIED 12Z INL RAOB FOR SFC T/TD OF 75/47 YIELDS SBCAPE UP TO 600
J/KG. ALTHOUGH SHRA COVERAGE IS STILL LIMITED OVER THE SCNTRL BY
LINGERING LLVL DRY AIR...EXPECT THESE SHRA TO SPREAD INTO THAT AREA
AS THE DRY AIR RETREATS. THE INTENSITY OF THE TS WL BE LIMITED BY
DRY LLVL AIR...ENVIRONMENTAL LAPSE RATES NOT FAR FM MOIST
ADIABATIC/DEEP SKINNY CAPE...LACK OF MID LVL DRY AIR THAT KEEPS
SFC-10K FT DELTA THETA-E NO HIER THAN 5-10C...AND RELATIVELY WEAK
DEEP LYR SHEAR NO GREATER THAN 15-25 KTS. ALTHOUGH SOME STORMS HAVE
PULSED AT TIMES...THE SMALL CORES HAVE NOT PERSISTED AND REMAINED
NEARLY VERTICAL...CONSISTENT WITH A WEAK SHEAR ENVIRONMENT. LO FRZG
LVL NOT FAR FM 9K FT AGL INDICATES THE STRONGER CELLS MIGHT DROP
SOME SMALL HAIL.
TONIGHT...MAIN FCST CONCERNS BECOME HOW QUICKLY DRIER AIR OVER
ONTARIO CAN MOVE INTO THE UPR LKS AND COUNTER LINGERING DYNAMIC
SUPPORT ASSOCIATED WITH DISTURBANCE NOW NEAR LK WINNIPEG THAT IS
FCST TO DROP SEWD INTO NW WI BY 12Z SUN AND SHARPEN UPR TROF AXIS
EXTENDING FM CLOSED LO NEAR JAMES BAY SWWD THRU UPR MI. LOSS OF
DAYTIME HEATING WL ALSO ENHANCE SHRA DISSIPATION. THE NAM IS MOST
AGGRESSIVE WITH UPR DRYING AND SHOWS ANY LINGERING -SHRA OVER THE
SCNTRL ENDING BY 03Z. THE BULK OF THE OTHER GUIDANCE MAINTAINS THE
-SHRA MAINLY OVER THE SCNTRL THRU MUCH OF THE NGT. HOWEVER...
CONSIDERING THE LLVL DRYNESS OF THE 12Z YPL RAOB AND RATHER
AGGRESSIVE DRYING TAKING PLACE OVER THE N PORTIONS OF LK SUP/
ADJOINING ONTARIO...THE NAM MIGHT BE ON THE RIGHT TRACK. SINCE ALL
THE MODELS ALSO SHOW LIMITED DEEP LYR QVECTOR CVNGC AS ANY DPVA
AHEAD OF SHRTWV IS OFFSET BY DRYING...TENDED TO CUT POPS A BIT
FASTER THAN GOING FCST WITH SMALL CHC POPS LINGERING ONLY OVER THE
FAR SCNTRL NEAR MNM LATER TNGT. ALTHOUGH LGT WINDS ASSOCIATED WITH
BLDG HI PRES MOVING TOWARD WRN UPR MI TOWARD 12Z/AGGRESSIVE MID LVL
DRYING MIGHT SUPPORT FOG FORMATION ESPECIALLY IN AREAS THAT GET RA
THIS AFTN/EVNG...WL KEEP FOG OUT OF FCST EXCEPT FOR OVER THE
INTERIOR WCNTRL...WHERE THE GFS HINTS THE LLVL DRYING WL BE LESS
PRONOUNCED AND SREF PROB VSBY UNDER 1 MILE IS HIER AND WHERE MIN
TEMPS ARE LIKELY TO BE LOWEST ARND 40.
SUN...CWA IS FCST TO REMAIN UNDER UPR TROF EXTENDING SWWD FM HUDSON
BAY. THE 12Z NAM/LOCAL WRF-ARW SHOW A SFC RDG AXIS EXTENDING FM WRN
LK SUP THRU THE CWA BRINGING A DRY DAY. THE 12Z GFS/CNDN MODELS ON
OTHER HAND SHOW A WEAKER SFC RDG...WITH A WEAKER GRADIENT ALLOWING
SOME LK BREEZE CNVGC/WEAK LO PRES TROF OVER THE SCNTRL...WHERE THESE
MODELS GENERATES SOME INSTABILITY -SHRA IN THE AFTN. CONSIDERING THE
WARM/DRY H7-5 LYR/LO FCST KINX ARND 18 BY THE GFS IN THIS AREA...
OPTED TO MAINTAIN GOING DRY FCST. WITH H85 TEMPS FCST TO BE ARND 8C
AND MIXING TO H75 ON GFS FCST SDNGS...EXPECT HI TEMPS TO REACH THE
MID 70S NEAR THE WI BORDER/SCNTRL AWAY FM LK MODERATION.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 359 PM EDT SAT AUG 18 2012
UPPER-LEVEL CONDITIONS WILL REMAIN SUPPORTIVE OF A SUBTLE SERIES OF
TROUGHS AND RIDGES THROUGH MONDAY. DRY CONDITIONS WILL THEN BUILD IN
FOR THE MIDDLE OF THE WEEK BEFORE A WARM...AND POTENTIALLY WET...END
TO THE WEEK.
SUNDAY NIGHT AND MONDAY...NAM/GFS/ECMWF/GEM HAVE COME INTO GOOD
AGREEMENT ON THE SYNOPTIC PATTERN ACROSS CENTRAL AND EASTERN NORTH
AMERICA THROUGH TUESDAY...SO OVERALL CONFIDENCE OF THE FORECAST IN
THIS TIME PERIOD IS FAIRLY GOOD.
A PERSISTENT MID-LEVEL LOW OVER JAMES BAY WILL BEGIN TO MOVE
NORTHEAST SUNDAY NIGHT AS A BROAD MID-LEVEL RIDGE OVER THE WESTERN
THIRD OF THE CONUS COMMENCES DEAMPLIFICATION WHILE DRIFTING EASTWARD
TOWARD THE UPPER GREAT LAKES REGION. A SERIES OF SHORTWAVE TROUGHS
WILL CONTINUE TO TRACK AROUND THE BACKSIDE OF THE LOW OVER JAMES
BAY. THE FIRST OF THOSE IS MOVING THROUGH THE AREA TODAY. THEN...A
SECOND TROUGH BEHIND TODAYS TROUGH WILL CROSS THE AREA ON
SUNDAY...AND BE EXITING TO THE SOUTHEAST OUT OF UPPER MI BY SUNDAY
EVENING. A SHORTWAVE RIDGE WILL THEN BRIEFLY MOVE IN SUNDAY EVENING
AHEAD OF YET ANOTHER WEAK SHORTWAVE TROUGH CROSSING THE CWA ON
MONDAY.
THE WEAK INCOMING RIDGE COMBINED WITH PLENTY OF DRY AIR THROUGHOUT
THE COLUMN SHOULD LIMIT THE CHANCE OF ANY PRECIP BY SUNDAY EVENING.
ATTENTION IS PLACED MOSTLY ON THE POTENTIAL OF TEMPERATURES NEARING
FROST CRITERIA/ 36F/ INTERIOR WEST SUNDAY NIGHT. DIFFICULTY OF
PINNING DOWN EXACT LOW TEMPS RESIDES WITH WINDS AND THE CLOUD COVER
PATTERN BETWEEN THE TROUGH ON MONDAY AND THE ONE ON TUESDAY.
FIRST...DRY AIR AND SUBSIDENCE WILL ERODE REMAINING CLOUDS FROM
SUNDAYS SHORTWAVE. SEVERAL MODELS ARE SHOWING AN ENHANCED LAYER OF
MOISTURE BETWEEN 800 AND 700MB MOVING INTO THE AREA LATE SUNDAY
NIGHT. THIS IS LIKELY RESIDUAL MOISTURE FROM DIURNAL CUMULUS ON
SUNDAY...AS IS NOTED WITH THE UPSTREAM SATELLITE IMAGES IN NORTHERN
MANITOBA...SO DO NOT THINK LOW CLOUDS WILL BE A FACTOR. AIR ABOVE
THE MID-LEVELS WILL BE QUITE DRY...WHICH IS ALSO NOTED ON IR/VIS
SATELLITE IMAGES FROM UPSTREAM. BEHIND A WEAK SFC RIDGE SUNDAY
EVENING...WINDS MAY END UP BEING THE LIMITING FACTOR AS THE PRESSURE
GRADIENT INCREASES WITH HIGH PRESSURE UNDER THE WESTERN RIDGE
BUILDING INTO THE REGION. THE LOW-LEVELS SHOULD BE ABLE TO DECOUPLE
ENOUGH...ESPECIALLY IN THE TYPICAL COLD SPOTS. ULTIMATELY...WILL
KEEP ONGOING FORECAST OF MID TO UPPER 30S WELL INLAND...AND LEAVE
PATCHY FROST OUT OF THE FORECAST FOR RIGHT NOW.
THE THIRD SHORTWAVE TROUGH IS PROGGED TO MOVE ACROSS THE CWA
THROUGHOUT THE DAY ON MONDAY. NOT MUCH IN THE WAY OF MOISTURE WITH
THIS SHORTWAVE EITHER. HOWEVER...AS THE INFLUENCE FROM THE TROUGH
APPROACHES THE SOUTH CENTRAL CWA...H8 WAA/MOISTURE TRANSPORT MAY
ASSIST WITH KICKING OFF SOME ISOLATED SHOWERS. LOW-LEVEL DRY AIR MAY
INHIBIT SHOWERS SOMEWHAT...SO WILL ONLY PUT A SLIGHT CHANCE IN THE
FORECAST FOR THE SOUTH-CENTRAL CWA. H8 TEMPS AROUND 7-8C SHOULD
YIELD HIGHS AROUND 70 FOR MOST LOCATIONS.
MONDAY NIGHT AND TUESDAY...THE DE-AMPLIFYING RIDGE FROM THE WESTERN
STATES WILL MOVE OVER UPPER MI MONDAY NIGHT...LEADING TO MOSTLY
CLEAR SKIES AND ANOTHER ROUND OF GOOD RADIATIONAL COOLING. THIS
TIME...DEW POINTS WILL BE MUCH HIGHER...SO MOST INLAND LOCATIONS
SHOULD STAY ABOVE 40. SUBSIDENCE FROM THE RIDGE WILL KEEP CONDITIONS
DRY THROUGH TUESDAY. H8 TEMPS FROM 10-12C WOULD RESULT IN MID 70S
FOR HIGHS ACROSS MOST OF THE CWA ON TUESDAY...WITH SLIGHTLY COOLER
TEMPS EAST IN REGIONS AFFECTED BY LAKE BREEZES FROM LAKES MICHIGAN
AND SUPERIOR.
TUESDAY NIGHT THROUGH SATURDAY...THE REMNANTS OF THE LOW CURRENTLY
OVER JAMES BAY WILL BE IN FAR NORTHERN QUEBEC BY TUESDAY NIGHT. A
SHORTWAVE TROUGH ROTATING AROUND THE BACK OF THE LOW IS PROGGED
TO MOVE THROUGH NORTHERN ONTARIO TUESDAY NIGHT INTO WEDNESDAY. THE
ECMWF HAS BEEN TRENDING FARTHER NORTH WITH THIS SYSTEM. MEANWHILE
THE GFS HAS BECOME THE MORE SOUTHERN SOLUTION. PREFER THE TREND OF
THE ECMWF AS THE WAVE WILL BE ATTEMPTING TO DIG INTO THE EASTERN
EDGE OF A NOW BUILDING WESTERN RIDGE. EXPECTATION IS THAT PRECIP
WILL STAY OUT OF THE AREA UNTIL LATE WEDNESDAY AS AN ASSOCIATED SFC
COLD FRONT STALLS OVER LAKE SUPERIOR...THOUGH THE FINAL LOCATION OF
THIS FEATURE IS STILL A LITTLE INCONSISTENT IN THE MODELS.
DRY AIR ABOVE THE LOWEST FEW KFT WILL ALLOW FOR DECENT MIXING ON
BOTH TUESDAY AND WEDNESDAY. LOWERED DAYTIME DEW POINTS ABOUT 5F FROM
PREVIOUS FORECAST FOR BOTH DAYS. THIS RESULTS IN MIN RH VALUES
AROUND 40 PERCENT BOTH DAYS. HOWEVER...FEELING IS THAT THE TREND
WILL BE TOWARD LOWER RH VALUES WITH PROCEEDING FORECASTS.
A DEEP TROUGH MOVING ONTO THE WEST COAST TUESDAY WILL THEN REACH THE
UPPER MS VALLEY BY LATE FRIDAY. THE INDUCED SFC LOW IS EXPECTED TO
BRING THE STALLED SFC BOUNDARY BACK NORTHWARD AS A WARM FRONT. HIGH
TEMPS DURING THIS TIME WILL LIKELY BE ABOVE NORMAL /AROUND 80/ DUE
TO SOUTHERLY FLOW SOUTH OF THE STALLED BOUNDARY...BUT AS NOTED
BEFORE...UNCERTAINTY STILL EXISTS IN THE FINAL LOCATION OF THE
BOUNDARY. WILL STICK WITH CONSENSUS OF MODEL THROUGHOUT THIS TIME
FRAME GIVEN DECENT AGREEMENT FOR THIS FAR OUT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 137 AM EDT SUN AUG 19 2012
AREAS OF FOG CONTINUE TO PLAGUE PORTIONS OF UPPER MICHIGAN ALTHOUGH
DRIER AIR IS ATTEMPTING TO MOVE INTO THE REGION FROM THE NORTH.
SATELLITE IMAGERY SHOWS NARROW SLOT OF CLEAR SKIES PUSHING INTO THE
AREA WITH AN AREA OF MID CLOUDS RIGHT BEHIND THIS FEATURE. CLEARING
SKIES AND SUBSIDENCE SUPPORTS PATCHY FOG DEVELOPMENT IN THOSE AREAS
THAT RECEIVED DECENT AMOUNTS OF RAINFALL. LESS ANTECEDENT MOISTURE
AT KCMX SUGGESTS FOG WILL NOT BE AS PREVALENT THERE. TAF FORECASTS
TO BE VERY TRICKY AT KIWD AND KSAW AS VIS AND CIGS WILL VARY
SIGNIFICANTLY FOR SOME TIME. ONCE THE INVERSION STRENGTHENS...MVFR
AND OCCASIONAL IFR CIGS/VIS TO PREVAIL. AS HIGH PRESSURE BUILDS INTO
THE AREA IN EARNEST...VFR CONDITIONS WILL THEN PREVAIL THROUGH THE
REMAINDER OF THE FORECAST.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT SAT AUG 18 2012
A GENERALLY WEAK PRES GRADIENT DOMINATING THE UPPER GREAT LAKES WILL
RESULT IN WINDS MOSTLY UNDER 20KT THRU THU. THE PRES GRADIENT WILL
BECOME A BIT SHARPER TUE NIGHT AS A LO PRES TROF MOVES ACROSS
CENTRAL ONTARIO...RESULTING IN WSW WINDS UP TO 25 KTS OVER PORTIONS
OF THE W AND NORTH CENTRAL.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TK
AVIATION...RJT
MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
350 AM CDT SUN AUG 19 2012
.DISCUSSION...
RATHER AMPLIFIED UPPER AIR PATTERN REMAINS IN PLACE THIS
MORNING...WITH SHARP UPPER RIDGE UP THE ROCKY MOUNTAINS FLANKED
BY A DEEP CLOSED LOW NEAR HUDSON BAY AND A LONGWAVE TROUGH OVER
THE NERN PAC. WITHIN THE NNW FLOW OVERHEAD...WATER VAPOR IMAGERY
AND RAP PV ANALYSIS SHOWS A POTENT WAVE DROPPING INTO CENTRAL MN
AT 8Z. AT THE SFC...HIGH PRESSURE WAS PARKED ACROSS MUCH OF THE
GREAT PLAINS WITH A WEAK FRONT/WIND SHIFT STILL EVIDENT IN THE FLOW
FROM MADISON...MN ACROSS THE TWIN CITIES AND OVER TOWARD GREEN
BAY.
ALOFT...PATTERN WILL UNDERGO A SLOW DE-AMPLIFICATION OVER THE
COMING DAYS. BY THE MIDDLE OF NEXT WEEK...WEAK ZONAL FLOW WILL BE
IN PLACE ACROSS MUCH OF THE CONUS AS ROCKIES RIDGE FLATTENS
OUT...THE HUDSON LOW FILLS/LIFTS NE AND THE PAC TROUGH MOVES INTO
BC AND UNDERGOES SOME DEEPENING. MEDIUM RANGE MODELS DO NOT BRING
THE WRN WAVE ACROSS THE CENTER OF THE CONTINENT UNTIL NEXT
WEEKEND.
AT THE SFC...FRONT SPLITTING THE MPX CWA NEARLY IN HALF THIS
MORNING WILL SLOWLY WASH OUT DURING THE DAY AS HIGH PRESSURE ACROSS
THE DAKOTAS PUSHES EAST. THIS HIGH PRESSURE WILL THEN SLOWLY TRACK
ACROSS THE UPPER MS VALLEY THROUGH TUESDAY NIGHT. WEDNESDAY...A
WEAK FRONTAL BOUNDARY WILL TRY TO SAG INTO THE LAKE SUPERIOR
REGION AS A LEE THROUGH SLOWLY TAKES SHAPE ACROSS THE HIGH PLAINS AS
UPPER FLOW BECOMES MORE ZONAL. THE FIRST FRONTAL PUSH FROM THIS
LEE TROUGHING LOOKS TO TRY AND PUSH INTO THE MPX AREA
THU/FRI...WITH A MORE SIGNIFICANT FRONT NOT LIKELY TO ARRIVE UNTIL
NEXT WEEKEND WITH THE STRONGER UPPER FORCING.
FOR TODAY THERE ARE TWO CONCERNS THANKS TO SHORTWAVE NOW IN
CENTRAL MN. FIRST IS HOW FAR NORTH TO KEEP POPS TODAY...WHILE THE
SECOND IS WHAT IMPACT WILL CLOUDS HAVE ON MAX TEMPS. FOR
PRECIP...TRIED LIMITING MENTIONABLE PRECIP TO WHERE MODELS SHOW
K-INDEX EXCEEDING 28. GOING BACK TO YESTERDAY...THIS MATCHED UP
FAIRLY WELL WITH WHERE SHOWERS/STORMS WERE ABLE TO FIRE OFF.
THOUGH MODELS DIFFER ON HOW QUICKLY THE H7 THROUGH/MOISTURE MAKE
IT THROUGH THE REGION...THEY ARE ALL FAIRLY SIMILAR WITH THEIR
K-INDEX FORECASTS...WHICH MATCHES UP WELL WITH 19.03 SREF PROBS.
HAVE HIGHEST POPS ACROSS SOUTH CENTRAL MN THIS MORNING...WITH ISO
STORMS LINGERING INTO THE AFTERNOON ALONG I-90. HOWEVER...THERE
IS SUPPORT FROM THE 19.00 ECMWF/GFS ALONG WITH HRRR REFLECTIVITY
FORECASTS FOR HAVE POPS FARTHER NORTH THAN CURRENTLY INDICATED FOR
TODAY. IF THE GFS/ECMWF ENDS UP BEING THE ROUTE THINGS TAKE FOR
TODAY...THEN IT WILL LIKELY END BEING MOSTLY CLOUDY ACROSS SOUTH
CENTRAL MN...WHERE HIGHS COULD END UP SEVERAL DEGREES COOLER THAN
CURRENTLY INDICATED.
PRECIP WILL QUICKLY CUT OFF THIS EVENING...WITH SKIES BECOMING
CLEAR. THIS WILL SET THE STAGE FOR RATHER TRANQUIL WEATHER FOR
SUNDAY THROUGH WEDNESDAY AS THE SFC HIGH SLOWLY SLIDES EAST. WITH
H5 HEIGHTS AND H85 TEMPS SLOWLY BUILDING DURING THIS PERIOD...WILL
SEE HIGHS TICK UP A COUPLE OF DEGREES EACH DAY. BY WEDNESDAY...THE
RETURN OF SOUTHERLY FLOW WILL HELP BOAST TEMPS BACK INTO THE
LOWER 80S...ALONG WITH SENDING DEWPS BACK INTO THE 60S.
FOR WEDNESDAY NIGHT THROUGH FRIDAY...UNCERTAINTY IN THE FORECAST
INCREASES QUITE A BIT. THOUGH THE MEDIUM RANGE MODELS GENERALLY
AGREE ON WEAK ZONAL FLOW SETTING UP ACROSS THE NRN CONUS THIS
PERIOD...THEY DIFFER ON THE HANDLING OF A SHORT WAVE PEGGED TO
MOVE THROUGH THIS FLOW FROM THURSDAY INTO FRIDAY. THE GFS
CONTINUES TO BE THE MOST AGGRESSIVE WITH THE WAVE...BRINGING A
NEGATIVELY TILTED SHORTWAVE AND ASSOCIATED COLD FRONT ACROSS THE
AREA THURSDAY NIGHT INTO FRIDAY. THE ECMWF SHOWS A MUCH
WEAKER/SLOWER WAVE WORKING INTO THE PLAINS...WITH VERY LITTLE IN
THE WAY OF PRECIP WORKING INTO THE AREA UNTIL THE WEEKEND FRONT.
FOR THIS PERIOD...FOLLOWED THE BLEND APPROACH WITH THE CONTINUED
MENTION OF 40-50 POPS THURSDAY NIGHT. HARD TO SAY WHICH WAY THINGS
MAY GO AT THIS POINT...BUT IT DOES APPEAR THE GFS IS SUFFERING
FROM SOME CONVECTIVE FEEDBACK WHICH IS LIKELY IMPACTING THE
STRENGTH OF SFC FEATURES IT SHOWS.
&&
.AVIATION... /06Z TAF ISSUANCE/
SHOWERS WILL SLOWLY DIMINISH EARLY THIS MORNING AS A COLD FRONT
FROM NORTHERN WI THROUGH CENTRAL MN MOVES SOUTHWARD. KRWF...KMSP
AND KEAU WILL HAVE A SHOWER AND ISOLATED THUNDERSTORM THREAT FOR
A FEW MORE HOURS. CLEARING OVER NORTHERN MN WILL BEGIN TO WORK
INTO KAXN...KSTC AND KRNH AFTER 08Z. THERE WILL LIKELY BE FOG
DEVELOPMENT AT KSTC AND KRNH WITH MVFR OR LOWER VISIBILITY.
CONCERN IS GROWING FOR IFR OR LOWER CEILINGS DEVELOPING. KEAU MAY
BE IN TROUBLE AS WELL BUT IT MAY BE TOWARDS DAYBREAK. HIGH
PRESSURE AND LIGHT NORTHERLY WINDS WILL OCCUR ON SUNDAY. THE CU
RULE IS RATHER NEGATIVE IN THE MORNING FROM KMSP THROUGH KEAU AND
HAVE INDICATED SOME BKN050 FOR KEAU WITH SCT050 FOR SITES TO THE
WEST.
KMSP...
A FEW SHOWERS ARE POSSIBLE THROUGH 08Z. CEILINGS BKN-OVC080-100
WILL LAST TO NEAR DAYBREAK THEN DIMINISH. SCT-BKN040 DEVELOPING
SUNDAY MORNING WITH CLR-SCT050 IN THE AFTERNOON. LIGHT NORTHWEST
WINDS DEVELOPING OVERNIGHT WITH NORTH WINDS 6 TO 9 KNOTS ON SUNDAY.
/OUTLOOK FOR KMSP/
MON...VFR. NORTHWEST 5 TO 10 MPH.
TUE...VFR. SOUTHWEST 5 TO 10 MPH.
WED...VFR. SOUTH 5 TO 10 MPH.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
MPG/RAH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1133 PM CDT SAT AUG 18 2012
.AVIATION...
06Z TAFS FOR KOMA...KLNK AND KOFK.
MID LEVEL CLOUDS AROUND 7000 TO 10000 FEET WILL CONTINUE TO MOVE
AWAY FROM KOMA AND KLNK OVERNIGHT. DUE TO LIGHT WINDS AND WET
GROUND FROM AREAS OF RAIN SATURDAY...AREAS OF FOG SHOULD DEVELOP.
THIS WOULD MAINLY BE AT KOMA AND KOFK...WHERE HAVE VISIBILITIES
TEMPORARILY GOING DOWN TO 3-4 MILES TOWARD SUNRISE. FOG SHOULD
BURN OFF BEFORE 15Z. ANOTHER WEAK DISTURBANCE IN THE FLOW WILL
DROP DOWN TOWARD THE AREA SUNDAY. THIS SHOULD CAUSE AN INCREASE
IN MID LEVEL CLOUDINESS. AT THIS TIME...FELT ANY SHRA WOULD NOT
AFFECT ANY OF THE TAF SITES.
MILLER
&&
.PREV DISCUSSION... /ISSUED 316 PM CDT SAT AUG 18 2012/
DISCUSSION...
SCATTERED SHOWERS CONTINUE TO SLIDE SOUTHEAST AS FORCING FOR
ASCENT FROM A MID LEVEL SHORTWAVE CONTINUES TO MOVE SOUTHEAST THRU
THE FORECAST AREA. THERE IS ANOTHER AREA OF SHOWERS IN A BAND TO
THE NORTHEAST OF THE CWA WHICH SEEMS TO LINE UP WELL WITH A NARROW
BAND OF MID LEVEL FRONTOGENESIS ON NOSE OF THETA-E AXIS. THIS
IS FORECAST TO CONTINUE SOUTHEAST THRU THE LATE AFTERNOON AND
EVENING HOURS SO WL CONTINUE TO INCLUDE A SMALL MENTION OF POPS IN
OUR EASTERN COUNTIES FOR THIS ACTIVITY AS WELL. IN
ADDITION...THERE IS A POTENTIAL FOR FOG DEVELOPMENT OVERNIGHT WITH
CLEARING SKIES. SFC WIND BECOMES LIGHT AND VARIABLE AS HIGH
PRESSURE MOVES OVER AREAS THAT SAW SOME PRECIPITATION TODAY.
LATEST HRRR ALSO SHOWING AREA OF REDUCED VISIBILITIES...ESPECIALLY
IN OUR NORTH SO WL GO AHEAD AND MENTION SOME PATCHY FOG OVERNIGHT.
EXPECTING LOWS TO FALL INTO THE UPPER 40S TO LOWER 50S WHICH
WILL BE CLOSE BUT SLIGHTLY ABOVE RECORDS.
SUNDAY CONTINUES TO LOOK MOSTLY DRY AS HIGH PRESSURE SLIDES EAST OF
THE AREA. MODELS CONTINUE TO INDICATE SOME LIGHT QPF IN OUR EASTERN
COUNTIES ASSOCIATED WITH EXITING UPPER LEVEL SHORTWAVE ENERGY. MAY
HAVE SOME ISOLATED SHOWERS OVER IOWA COUNTIES IN THE AFTERNOON
ONCE CU FIELD DEVELOPS. WILL THROW IN A SLIGHT CHANCE POP IN OUR
FAR NERN COUNTIES FOR SUNDAY AFTERNOON AND MENTION ISOLATED
THUNDER AS SOME INSTABILITY IS PRESENT.
AREA REMAINS IN NORTHWESTERLY FLOW FOR EARLY IN THE SCHOOL/WORK
WEEK. THE WEATHER SHOULD REMAIN FAIRLY QUIET WITH WARM SOUTHERLY
FLOW BRINGING A SLIGHT INCREASE IN LOW LEVEL MOISTURE TO THE
AREA.
IN THE EXTENDED...MID LEVEL FLOW WILL BECOME MORE ZONAL BY MID
WEEK AS WEAKENING UPPER LEVEL RIDGE FLATTENS OVER THE NATIONS MID
SECTION. A POTENT SHORTWAVE MOVING INTO THE NORTHERN PLAINS BY
LATE IN THE WEEK WILL DRIVE A COOL FRONT THRU THE CENTRAL PLAINS.
AHEAD OF THIS BOUNDARY...LOW LEVEL WARM AIR AND MOIST ADVECTION
COULD LEAD TO A SCATTERED CHANCE OF SHOWERS AND THUNDERSTORMS
THURSDAY. SEVERE THREAT WOULD LIKELY REMAIN FAR TO OUR
NORTH...CLOSER TO POTENT SHORTWAVE ENERGY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
330 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF DISTURBANCES ALOFT PASSING TODAY INTO TUESDAY. THE DEEPER
MOISTURE FOR THESE FEATURES TO TAP...MAINLY FROM MOUNTAINS ON EAST.
WEAK HIGH PRESSURE FOR WEDNESDAY THROUGH THE END OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
BROAD MID/UPPER LEVEL TROF HERE FOR SEVERAL DAYS.
BASING FORECAST ON A STRONGER LEADING 500 MB VORT MAX PASSING FROM
SOUTHWEST TO NORTHEAST 12Z TO 16Z...EXITING THE NRN WV MOUNTAINS
AROUND 17Z. SO WILL BE FASTER IN INCREASING CLOUDS AND POPS EARLY
THIS MORNING OVER THE MOUNTAINOUS COUNTIES...PEAKING IN POCAHONTAS
COUNTY AROUND 15/16Z. DID NOT MENTION THUNDER. AS A RESULT OF THE
THICKENING AND LOWERING CLOUDS...REDUCE ANY THICK VALLEY FOG.
ONCE THAT FEATURE EXITS...HARD TO DETERMINE IF ANY SHOWERS DEVELOP
FURTHER WEST...ACROSS THE LOWLANDS DURING THE AFTERNOON AND
EVENING. SOME OF THE NEAR TERM MODELS...LIKE THE HRRR AND WRF-NMM
ARE DEVELOPING SHOWERS...MAYBE RELATED THE THE LOW LEVEL DEW POINT
GRADIENT BEING SHOVED BACK NORTHWEST TODAY. WILL TRY TO KEEP MOST
POPS IN WAKE OF THIS MORNINGS FEATURE...IN THE 20 OR LESS
CATEGORY...THINKING THE MAXIMUM IN MOISTURE IN THE OHIO VALLEY WILL
MOVE INTO NORTHERN HALF OF OHIO BY LATE THIS AFTERNOON...NOT THE
SOUTHERN COUNTIES.
00Z NAM WAS FASTER THAN THE 00Z GFS IN REDUCING MEAN RELATIVE
HUMIDITY IN THE COLUMN TONIGHT. FOR NOW...DO NOT SEE ANY REASON TO
ADJUST OUR 20/SLIGHT CHANCE POPS.
ALSO...DEPENDING ON THE RAIN TODAY...VALLEY FOG MAY HAVE TO BE
INSERTED FOR 06Z TO 12Z MONDAY...BUT A BIT PREMATURE AT THIS TIME.
COULD NOT HOLD MAXIMUM TEMPERATURES DOWN TOO MUCH TODAY...SINCE
HAVING THE MAIN SUPPORT EXITING BEFORE 18Z.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
MODELS CONTINUE TO INDICATE 500MB TROUGH APPROACHING REGION HEADED
INTO SHORT TERM...WITH SEVERAL IMPULSES LIFTING THROUGH DURING THE
FIRST HALF OF THE WEEK. THE BEST MOISTURE IS GENERALLY IN THE WV
MOUNTAINS AND TO THE SOUTH EAST AND IT LOOKS LIKE THE MAIN SURFACE
LOW SHOULD ALSO STAY SOUTH EAST...SO KEPT HIGHEST POPS IN THE
MOUNTAINS DURING THE AFTERNOONS. MONDAY LOOKS LIKE THE DAY FOR THE
MOST COVERAGE OF PRECIP...AND HAVE CHANCE POPS FROM MOUNTAINS BACK
TO ABOUT THE OHIO RIVER...WITH SLIGHT CHANCE POPS INTO SE OHIO. POPS
LINGER INTO MONDAY NIGHT AS MODELS SHOW MOISTURE REMAINING WITH A
LITTLE RIPPLE ALOFT. SOME DIFFERENCES IN PLACEMENT BETWEEN
MODELS...BUT IN GENERAL SHOWING ANOTHER WEAK SHORTWAVE MOVING
THROUGH FOR TUESDAY AFTERNOON. BEST MOISTURE IS PROGGED TO BE
FARTHER EAST THAN ON MONDAY...SO KEPT CHANCE POPS MORE CLOSELY TIED
TO MOUNTAINS. MODELS SHOW RISING HEIGHTS HEADED INTO TUESDAY...AND
PUSH BEST MOISTURE EVEN FATHER EAST...SO LOOKS LIKE A DRIER DAY WITH
MAYBE JUST AN ISOLATED SHOWER IN MOUNTAINS.
ONLY MINIMAL CHANGES TO TEMPS THIS PACKAGE...STILL LOOKS LIKE A
GRADUAL WARMING TREND INTO MIDWEEK WITH NEAR NORMAL TEMPERATURES BY
WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED A BLEND OF THE GFS AND ECMWF FOR WEDNESDAY THROUGH FRIDAY. THIS
LEAVES A WEAK HIGH PRESSURE SYSTEM OVER THE REGION...BUT POSSIBLY
ENOUGH MOISTURE TO FIRE SOME AFTERNOON SHOWERS/THUNDERSTORMS IN THE
MOUNTAINS. BY SATURDAY...SWITCHED TO A BLEND OF THE ECMWF AND GEFS
MEAN.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
WITH HIGH CLOUDS THICKENING AND LOWERING IN ADVANCE OF FIRST
WAVE...WAS A BIT MORE OPTIMISTIC ON THE FOG 06Z TO 12Z. STILL
ALLOWED FOR SOME LOCAL IFR IN NRN WV INCLUDING EKN DUE TO THE
THINNER CLOUDS.
THE 500 MB VORT MAX PASSES AROUND 15Z TO 18Z. BKW TO EKN CORRIDOR
SHOULD BE TOWARD THE WESTERN EDGE OF THE MAIN SHOWER SHIELD
ASSOCIATED WITH THIS WEAVE. HAVE POPS PEAKING ABOUT 15Z TO 17Z
AROUND POCAHONTAS COUNTY...BEFORE LOWERING AGAIN DURING THE 18Z TO
21Z PERIOD. HAVE CEILINGS LOWERING ALONG THE EASTERN SLOPES INTO
THE 2 TO 3 THSD FT BKN RANGE AND VSBY AROUND 5 MILES IN ANY RAIN
SHOWERS.
FURTHER WEST HAVE MID DECK AROUND 10 THSD FT AT 12Z BEFORE SOME 4 TO
6 THSD FT CEILINGS FROM BETWEEN 12Z TO 18Z.
ONCE THAT SUPPORT EXITS...HAVE TO GET A HANDLE ON THE AMOUNT AND
HEIGHTS OF THE CLOUDS FOR SUNDAY EVENING...SAY 00Z TO 06Z. WILL
LEAVE A SLIGHT CHANCE OF SHOWERS IN OVERNIGHT...WITH WEAKER
DISTURBANCES ALOFT...COMPARED TO TODAY. VISIBILITY IN THE MOUNTAIN
VALLEYS WILL LIKELY DEPEND ON ANY RAIN TODAY...SO WILL HAVE TO BE
FINE TUNED LATER TODAY. THE MEDIUM CONFIDENCE MAINLY HAS TO DO WITH
THESE UNCERTAINTIES.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: THICKER FOG IN RIVER VALLEYS IF CLOUDS REMAIN
THIN LONGER DURING THE PREDAWN. FOG MAY FORM QUICKER LATE SUNDAY
EVENING IF RAIN IS MORE WIDESPREAD IN THE MOUNTAINOUS COUNTIES
TODAY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 08/19/12
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY M M M H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L L L M H H H H H H H
PKB CONSISTENCY M M M M H H H H H H H H
CKB CONSISTENCY L L M M H H H H H H H H
AFTER 06Z MONDAY...
AREAS OF FOG MAY CAUSE IFR 06Z TO 12Z MONDAY DEPENDING ON CLOUD
COVER AND PREVIOUS RAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/RPY/MZ
NEAR TERM...KTB
SHORT TERM...MZ
LONG TERM...RPY
AVIATION...KTB
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
205 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE WILL SLIDE EASTWARD FROM THE LOWER
LAKES EARLY THIS MORNING. THE LARGE SCALE PATTERN INTO EARLY NEXT WEEK
WILL REMAIN DOMINATED BY A DEEP UPPER LEVEL TROUGH ENCOMPASSING
MUCH OF EASTERN NORTH AMERICA. A WAVE OF LOW PRESSURE IS FORECAST
TRACK NORTHEASTWARD ACROSS THE MID-ATLANTIC STATES LATER SUNDAY
THROUGH MONDAY. HIGH PRESSURE SHOULD RETURN TO THE AREA BY THE
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
CIRRUS CONTINUES TO STREAM OVER CENTRAL PA THIS EVENING...AND HAVE
THUS RAISED MIN TEMPS A BIT...ESP ACROSS THE SW PORTION OF CWA.
BASED ON HRRR AND DEWPOINT DEPRESSIONS...HAVE KEPT PATCHY VALLEY
FOG IN THE FCST FOR LATE TONIGHT...ESP OVR THE NW MTNS. HAVE
ADDED PATCHY FOG TO THE LOW LYING REGIONS ALONG THE LOWER
SUSQ...GIVEN THE CALM WINDS AND THE DEWPOINT DEPRESSIONS. HOWEVER...IF
APPROACHING CIRRUS SHIELD IS THICK ENOUGH...MAY HAVE TO REMOVE IT.
FOR THOSE AREAS THAT REMAIN MCLEAR... THIS COULD BE THE COOLEST
NIGHT SINCE LAST JUNE WITH LOWS RANGING FROM THE L40S IN THE
COOLEST HOLLOWS OF THE NORTH...TO THE M50S ACROSS THE LOWER SUSQ
VALLEY.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
FAST-MOVING SHORTWAVE...ROUNDING BASE OF UPPER TROF OVR THE MISS
VALLEY THIS EVENING...SHOULD LIFT NE ACROSS OUR REGION DURING LATE
AM/EARLY AFTN SUNDAY. ALTHOUGH LL FLOW WILL SHIFT TO THE SOUTH
AHEAD OF THIS FEATURE...MOISTURE WILL REMAIN LIMITED. BEST CHC FOR
A FEW -SHRA WILL BE ACROSS SOUTH CENTRAL PA DURING THE LATE
AM/EARLY AFTN HOURS. TOWARD EVENING...EXPECT WANING CHC OF SHRA
ACROSS THE EAST. HOWEVER...STEEPENING LPS RTS AHEAD OF NEXT
SHORTWAVE SHOULD BE SUFFICIENT TO PRODUCE ISOLD EVENING SHRA OR
TSRA ACROSS THE W MTNS BEFORE SUNSET. DESPITE MORE CLOUD
COVER...HIGH TEMPS SUNDAY SHOULD BE SIMILAR TO SAT...RANGING FROM
THE L70S OVR THE ALLEGHENIES...TO NR 80F IN THE SUSQ VALLEY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
FANTASTIC AGREEMENT AMONGST ALL FORECAST MODELS AND ENSEMBLE MEANS
OF THE MAJOR UPPER LEVEL FEATURES LEADS TO A HIGHER-THAN-NORMAL
CONFIDENCE FORECAST FOR THE LONG TERM. A HIGHLY ANOMALOUS UPPER
TROUGH OVER THE CENTRAL AND SOUTHERN STATES AT THE START OF THE
PERIOD WILL FILL AND LIFT EASTWARD DURING THE MID-WEEK.
THUS...TEMPS SHOULD BE SLIGHTLY BELOW NORMAL. PATTERN IS THEN
MAINLY ZONAL. SFC FEATURES WILL DRIVE MINOR FORECAST UNCERTAINTIES
IN THE FIRST FEW DAYS...THOUGH. A STALLED FRONT OVER THE SOUTHERN
MID-ATLANTIC COULD BUCKLE A BIT NORTHWARD AS A MOISTURE PLUME
WITH A CONNECTION TO DEEP TROPICAL MOISTURE OVER MEXICO IS DRAWN
NORTHWARD ON THE EASTERN SIDE OF THE UPPER TROUGH. A WAVE HAS BEEN
FORECAST TO DEVELOP ALONG THE FRONT FOR THE PAST FEW RUNS...AND
SEE NO REASON TO DISCOUNT THAT WITH SUCH A GOOD FEED ALOFT. THE
CHANCES OF PRECIP ARE VERY MUCH IN QUESTION...THOUGH. WILL HOLD
WITH MUCH OF THE CURRENT FORECAST...AND KEEP CHC RANGE POPS IN FOR
MAINLY THE EAST SUN NIGHT - MON NIGHT. AS BEFORE...HIGHEST POPS OF
LIKELIES WILL BE OVER THE SERN COS FOR MONDAY. NO THREAT FOR HEAVY
RAIN WITH NO REAL LOCAL FOCUS...AND THE WAVE ALONG THE FRONT
SHOULD BE MOBILE. TUESDAY AFTERNOON MAY HOLD SCT TSRA WITH COOL
TEMPS ALOFT AS THE TROUGH AXIS WILL BE OVERHEAD OR JUST
APPROACHING. THEN MUCH OF THE WEEK LOOKS DRY AS A SFC ANTICYCLONE
SETTLES IN FOR THE LONG HAUL. D7/D8 WILL SEE THE RETURN OF VERY
LOW POPS TO THE WEST AS THE HIGH SLIDES TO THE EAST INTO THE
WESTERN ATLANTIC.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
IR SATL LOOP SHOWS MULTI-LYRD CLOUD SHIELD STREAMING ENEWD FM THE
OH VLY AND CENTRAL APPLCHNS. THESE CLOUDS WILL CONTINUE TO OVERSPREAD
THE REGION THRU THE PREDAWN HOURS AND LIMIT FURTHER DIURNAL
COOLING. THEREFORE...REMOVED MUCH OF THE FOG IN THE PREVIOUS TAFS
WITH THE BEST CHANCE OF RESTRICTIONS LKLY AT IPT/BFD.
A BROAD UPPER LEVEL TROUGH EXTENDING SWD FROM JAMES BAY VORTEX
WILL PERSIST THROUGH EARLY NEXT WEEK. SEVERAL IMPULSES WILL
TRANSLATE AROUND THE BASE OF THE TROUGH THRU THE MS/TN/OH
VLYS AND INTERACT WITH A WAVY FRONTAL BOUNDARY STRETCHING FROM THE
DEEP SOUTH INTO THE SRN MID-ATLC STATES. THERE IS A LARGE SPREAD IN
PCPN DETAILS ASSOCIATED WITH THESE FEATURES...AND THIS TRANSLATES
INTO A LOW CONFIDENCE AVN FCST. IN GENERAL...WENT WITH A GRADUAL
LOWERING OF CLOUD BASES INTO THE LOW END VFR OR MVFR RANGE BY THE
END OF THE PD/06Z MON. CONSENSUS OF MDL DATA WOULD TEND TO FAVOR
THE S-CENTRAL/SERN TERMINALS FOR THE HIGHEST PROBABILITY FOR PCPN
THRU EARLY NEXT WEEK.
OUTLOOK...
MON-TUE...VFR/MVFR WITH PERIODS OF LGT PCPN PSBL ESP SRN AIRFIELDS.
WED-THUR...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...FITZGERALD/CERU
SHORT TERM...DEVOIR/FITZGERALD
LONG TERM...DANGELO
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
127 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE WILL SLIDE EASTWARD FROM THE LOWER
LAKES EARLY THIS MORNING. THE LARGE SCALE PATTERN INTO EARLY NEXT WEEK
WILL REMAIN DOMINATED BY A DEEP UPPER LEVEL TROUGH ENCOMPASSING
MUCH OF EASTERN NORTH AMERICA. A WAVE OF LOW PRESSURE IS FORECAST
TRACK NORTHEASTWARD ACROSS THE MID-ATLANTIC STATES LATER SUNDAY
THROUGH MONDAY. HIGH PRESSURE SHOULD RETURN TO THE AREA BY THE
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
CIRRUS CONTINUES TO STREAM OVER CENTRAL PA THIS EVENING...AND HAVE
THUS RAISED MIN TEMPS A BIT...ESP ACROSS THE SW PORTION OF CWA.
BASED ON HRRR AND DEWPOINT DEPRESSIONS...HAVE KEPT PATCHY VALLEY
FOG IN THE FCST FOR LATE TONIGHT...ESP OVR THE NW MTNS. HAVE
ADDED PATCHY FOG TO THE LOW LYING REGIONS ALONG THE LOWER
SUSQ...GIVEN THE CALM WINDS AND THE DEWPOINT DEPRESSIONS. HOWEVER...IF
APPROACHING CIRRUS SHIELD IS THICK ENOUGH...MAY HAVE TO REMOVE IT.
FOR THOSE AREAS THAT REMAIN MCLEAR... THIS COULD BE THE COOLEST
NIGHT SINCE LAST JUNE WITH LOWS RANGING FROM THE L40S IN THE
COOLEST HOLLOWS OF THE NORTH...TO THE M50S ACROSS THE LOWER SUSQ
VALLEY.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
FAST-MOVING SHORTWAVE...ROUNDING BASE OF UPPER TROF OVR THE MISS
VALLEY THIS EVENING...SHOULD LIFT NE ACROSS OUR REGION DURING LATE
AM/EARLY AFTN SUNDAY. ALTHOUGH LL FLOW WILL SHIFT TO THE SOUTH
AHEAD OF THIS FEATURE...MOISTURE WILL REMAIN LIMITED. BEST CHC FOR
A FEW -SHRA WILL BE ACROSS SOUTH CENTRAL PA DURING THE LATE
AM/EARLY AFTN HOURS. TOWARD EVENING...EXPECT WANING CHC OF SHRA
ACROSS THE EAST. HOWEVER...STEEPENING LPS RTS AHEAD OF NEXT
SHORTWAVE SHOULD BE SUFFICIENT TO PRODUCE ISOLD EVENING SHRA OR
TSRA ACROSS THE W MTNS BEFORE SUNSET. DESPITE MORE CLOUD
COVER...HIGH TEMPS SUNDAY SHOULD BE SIMILAR TO SAT...RANGING FROM
THE L70S OVR THE ALLEGHENIES...TO NR 80F IN THE SUSQ VALLEY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
FANTASTIC AGREEMENT AMONGST ALL FORECAST MODELS AND ENSEMBLE MEANS
OF THE MAJOR UPPER LEVEL FEATURES LEADS TO A HIGHER-THAN-NORMAL
CONFIDENCE FORECAST FOR THE LONG TERM. A HIGHLY ANOMALOUS UPPER
TROUGH OVER THE CENTRAL AND SOUTHERN STATES AT THE START OF THE
PERIOD WILL FILL AND LIFT EASTWARD DURING THE MID-WEEK.
THUS...TEMPS SHOULD BE SLIGHTLY BELOW NORMAL. PATTERN IS THEN
MAINLY ZONAL. SFC FEATURES WILL DRIVE MINOR FORECAST UNCERTAINTIES
IN THE FIRST FEW DAYS...THOUGH. A STALLED FRONT OVER THE SOUTHERN
MID-ATLANTIC COULD BUCKLE A BIT NORTHWARD AS A MOISTURE PLUME
WITH A CONNECTION TO DEEP TROPICAL MOISTURE OVER MEXICO IS DRAWN
NORTHWARD ON THE EASTERN SIDE OF THE UPPER TROUGH. A WAVE HAS BEEN
FORECAST TO DEVELOP ALONG THE FRONT FOR THE PAST FEW RUNS...AND
SEE NO REASON TO DISCOUNT THAT WITH SUCH A GOOD FEED ALOFT. THE
CHANCES OF PRECIP ARE VERY MUCH IN QUESTION...THOUGH. WILL HOLD
WITH MUCH OF THE CURRENT FORECAST...AND KEEP CHC RANGE POPS IN FOR
MAINLY THE EAST SUN NIGHT - MON NIGHT. AS BEFORE...HIGHEST POPS OF
LIKELIES WILL BE OVER THE SERN COS FOR MONDAY. NO THREAT FOR HEAVY
RAIN WITH NO REAL LOCAL FOCUS...AND THE WAVE ALONG THE FRONT
SHOULD BE MOBILE. TUESDAY AFTERNOON MAY HOLD SCT TSRA WITH COOL
TEMPS ALOFT AS THE TROUGH AXIS WILL BE OVERHEAD OR JUST
APPROACHING. THEN MUCH OF THE WEEK LOOKS DRY AS A SFC ANTICYCLONE
SETTLES IN FOR THE LONG HAUL. D7/D8 WILL SEE THE RETURN OF VERY
LOW POPS TO THE WEST AS THE HIGH SLIDES TO THE EAST INTO THE
WESTERN ATLANTIC.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
NO CHANGE TO 03Z TAF PACKAGE.
EARLIER DISCUSSION BELOW.
SPENT SOME TIME AROUND 21Z ADJUSTING THE FCST. WHILE SOME CU AND
SC MAY MOVE INTO CENTRAL PA SUNDAY MORNING...HARD TO SEE FOG
STAYING AROUND VERY LONG. THUS 21Z TAFS ARE ABOUT THE SAME AS THE
00Z TAFS...MADE CHANGES AT 21Z INSTEAD OF WAITING UNTIL 00Z.
FOR TONIGHT...WE HAD A NICE SUNNY DAY TO DRY THINGS OUT FOR
A CHANGE. OTHER THAN BFD AND JST...WHICH ARE CLOSER TO THE SFC
RIDGE AXIS LATE TONIGHT...HARD TO SEE MUCH FOG AND LOW CIGS
FORMING. IPT MAY HAVE SOME LOWER CIGS LATE...BUT NOT LOOKING AT
MUCH FOG... GIVEN THAT OFTEN THE LOWER CIG GETS GOING FAST...AND
THIS SLOWS FURTHER COOLING. SOME THIN...PATCHY FOG POSSIBLE TOWARD
SUNRISE AT OTHER SITES.
EXPECT VFR CONDITIONS TO RETURN BY MID MORNING ON SUNDAY. SOME
CU AND SC COULD WORK IN ACROSS WESTERN AND SOUTHERN AREAS...BUT
EXPECT CIGS TO BE VFR WHERE THE CLDS ARE BKN. ALSO HELD OFF
MENTION OF SHOWERS PRIOR TO 00Z.
WHILE THIS SOME POTENTIAL FOR SHOWERS FROM LATE SUNDAY INTO
MONDAY...NOT SURE IF MODELS ARE HAVING PROBLEMS WITH TOO MUCH
PHASING OF UPPER LVL ENERGY AND SEVERAL WEAK FRONTS.
STILL THINK BEST CHC OF LOWER CIGS AND SHOWERS WOULD BE SOUTH
OF CENTRAL PA.
OUTLOOK...
SUN NIGHT-MON...BECOMING MVFR CONDITIONS WITH SHOWERS...PERHAPS
IFR AT TIMES.
TUE-THU...MAINLY VFR...ISOLD MVFR CIGS WITH -SHRA STILL POSSIBLE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...FITZGERALD/CERU
SHORT TERM...DEVOIR/FITZGERALD
LONG TERM...DANGELO
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1134 PM CDT SAT AUG 18 2012
.AVIATION...
ISOLATED -TSRA HAVE DEVELOPED IN THE VICINITY OF KLBB AT 0430Z AND
THIS ACTIVITY COULD LINGER PAST 0600Z...BUT CONFIDENCE IS LOW.
OTHERWISE...CAN/T TOTALLY RULE OUT A PASSING SHRA/TSRA AT EITHER
TERMINAL THROUGH THE NIGHT...BUT CHANCES ARE WELL TOO LOW TO
MENTION IN TAF. ALSO...SOME LIGHT FOG MAY DEVELOP IN THE VICINITY
OF KLBB BETWEEN 0600 AND 1200Z...AFTER WHICH NORTHERLY WINDS AND
SLIGHTLY DRIER AIR SHOULD SCOUR OUT ANY FOG. VFR CONDITIONS ARE
EXPECTED FOR THE REMAINDER OF SUNDAY WITH AN OUTSIDE CHANCE OF A
THUNDERSTORM.
&&
.PREV DISCUSSION... /ISSUED 1039 PM CDT SAT AUG 18 2012/
UPDATE...
WE/VE TRIMMED POPS BACK FOR THE REMAINDER OF THE NIGHT. ASIDE FROM
THE PERSISTENT SEVERE STORM NOW MOVING ACROSS COCHRAN
COUNTY...ONLY A FEW ISOLD SHOWERS WERE PRESENT ACROSS THE FA. THERE
IS STILL SOME WEAK MID-LVL ENERGY IN THE NW FLOW ALOFT
MAINTAINING SOME SHOWERS IN NE NEW MEXICO...AND THIS ACTIVITY MAY
MAKE IT INTO OUR NW ZONES AFTER MIDNIGHT. OTHERWISE...WEAK ISENTROPIC
LIFT OF THE RELATIVELY MOIST AIRMASS WILL KEEP AN ISOLD
SHOWER/WEAK TSTM POTENTIAL GOING OVERNIGHT ACROSS THE ENTIRE AREA.
PREV DISCUSSION... /ISSUED 638 PM CDT SAT AUG 18 2012/
AVIATION...
VFR CONDITIONS EXPECTED FOR KCDS.
FOR KLBB...AN OUTFLOW BOUNDARY TO THE EAST OF KLBB SHOULD MOVE WEST
ACROSS THE TERMINAL IN THE 00Z TO 02Z TIME FRAME WITH TCU AND
POSSIBLY -TSRA IN THE VICINITY OF KLBB. ADDITIONALLY...THERE IS
A LOW PROBABILITY THAT TSRA ACTIVITY CURRENTLY IN THE TX PANHANDLE
COULD MOVE SOUTH AND IMPACT KLBB SOMEWHERE IN THE 03Z TO 09Z TIME
FRAME. OTHERWISE...SURFACE WINDS WILL TEND MORE TO THE NORTHEAST
AND NORTH AS OUTFLOW BOUNDARIES AND A WEAK COLD FRONT MOVE ACROSS
EARLY SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 551 PM CDT SAT AUG 18 2012/
UPDATE...
QUICK UPDATE TO REMOVE HALL...CHILDRESS AND COTTLE COUNTIES FROM
THE SEVERE THUNDERSTORM WATCH. OVERALL...STORM INTENSITY HAS BEEN
RATHER TAME...THOUGH A FEW CELLS DO OCCASIONALLY PULSE UP. IN
ADDITION...A SMALL CLUSTER OF STORMS COULD GENERATE GUSTY WINDS AS
THEY MOVE THROUGH THE SOUTHEASTERN ZONES OVER THE NEXT HALF HOUR
TO HOUR. UPDATED PRODUCTS HAVE BEEN SENT.
PREV DISCUSSION... /ISSUED 339 PM CDT SAT AUG 18 2012/
SHORT TERM...
WELL-DEFINED OUTFLOW BOUNDARY/COMPOSITE COLD FRONT WAS MOVING
SOUTHWEST INTO CHILDRESS AND HALL COUNTIES JUST NORTH OF A SURFACE
TROUGH STRETCHING FROM NEAR DIMMITT ESE TO SWEARINGEN. THE TRUE COLD
FRONT OF INTEREST THAT IS PROGGED TO DROP HIGHS BELOW NORMAL ON
SUNDAY /UNDER MOSTLY SUNNY SKIES!/ WAS FOUND DIVING SOUTH ACROSS WRN
KANSAS AND ERN COLORADO. BRUNT OF THE PRECIP POTENTIAL WILL BE
RELEGATED TO THE PRE-FRONTAL BOUNDARIES CURRENTLY CONVECTING ACROSS
THE NRN HALF OF THE CWA. ALTHOUGH WIND SHEAR IS WEAK THUS FAR...THIS
WILL IMPROVE AS THE AFTERNOON AND EARLY EVENING WEAR ON COURTESY OF
A SHORTWAVE TROUGH AND ASSOCIATED WIND MAX APPROACHING IN NORTHWEST
FLOW. EVEN WITH MLCAPES GENERALLY AOB 1000 J/KG...THIS IMPROVING
LIFT SHOULD SECURE A WINDOW FOR ORGANIZED SEVERE STORMS MAINLY IN
THE FORM OF SMALL SEGMENTS OR LINES WITH DMGG WINDS THE GREATEST
THREAT BEFORE INTENSITY AND STORM COVERAGE WANE BY LATE EVENING.
CURRENT SVR WATCH CAPTURES THIS THREAT WELL...BUT MAY REQUIRE
EXPANSION SWWD SHOULD TRENDS WARRANT. A FEW HI-RES MODELS SUCH AS
THE TTU WRF AND HRRR DO INDICATE SUCH A SCENARIO FOR LUBBOCK AND
POINTS SOUTHWEST...SO THIS WILL BE MONITORED CLOSELY BY THE ONCOMING
SHIFT. OTHERWISE...FROPA WILL OCCUR AFTER MIDNIGHT FOLLOWED BY
DIMINISHING POPS. MOIST POST-FRONTAL UPSLOPE TOMORROW AFTN IN ERN NM
AND ADJACENT COUNTIES OF THE TX SOUTH PLAINS STILL APPEARS
REASONABLE FOR SLIGHT CHANCE POPS IN OUR SWRN COUNTIES...HOWEVER THE
NAM LOOKS MUCH TOO BULLISH WITH QPF IN SUCH A REGIME AND IS LARGELY
BEING DISMISSED
LONG TERM...
NNW FLOW ALOFT IS EXPECTED ON MONDAY. HIGH AMPLITUDE RIDGE WILL
SPAN FROM NWRN MEXICO UP TO NORTHERN ALBERTA. OUT EAST...MATURE LOW
WILL BE SITUATED OVER THE SRN PART OF HUDSON BAY WITH AN EMBEDDED
SHORTWAVE DUE INTO THE CENTRAL PLAINS EARLY ON TUESDAY ALTHOUGH THE
BEST ENERGY ASSOCIATED WITH THIS SYSTEM WILL LIKELY REMAIN NORTHEAST
OF THE REGION. BY MID WEEK...THE RIDGE WILL BEGIN TO MOVE EASTWARD
AND FLATTEN WITH SOME HINTS IN BOTH THE GFS AND ECM ABOUT A BIT OF A
DISTURBANCE PASSING TO OUR NORTH ON THURSDAY. WHILE THE ECM
SOLUTION WOULD BE MORE FAVORABLE INTO BRINGING A FRONT INTO THE
REGION...AND PRECIPITATION...THE GFS HAS MORE CLOSELY PARALLELED
REALITY FOR THE PAST WEEK AND THUS WILL TREND THE FORECAST IN THAT
DIRECTION.
GIVEN NWP PERFORMANCE AS OF LATE WRT QPF AM NOT COMPLETELY CONVINCED
THAT WE WILL SEE AS MUCH RAIN ACROSS THE REGION AS PREVIOUSLY
THOUGHT...BUT HAVE ELECTED ONLY TO MAKE A DOWNWARD TREND OF MONDAY
NIGHT POPS. LIKE TODAY...VIRTUALLY EVERY MODEL CONVECTS BUT PRECIP
HAS BEEN HARD TO COME BY. AS PREVIOUSLY MENTIONED...SHORTWAVE
PASSES TO OUR NORTH SOMETIME ON THURSDAY BUT AGAIN...CONFIDENCE IN
MEANINGFUL RAINFALL IS TOO LOW FOR MENTION IN THE WX GRIDS ATTM.
GIVEN THAT...MOST OF THE EXTENDED LOOKS DRY ALTHOUGH WE WOULD LOVE
TO BE WRONG ABOUT THAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 61 83 57 85 58 / 20 10 10 20 30
TULIA 63 83 61 85 60 / 20 10 10 10 30
PLAINVIEW 64 82 61 88 63 / 20 10 10 10 30
LEVELLAND 66 83 61 89 63 / 40 20 10 10 30
LUBBOCK 67 84 62 90 65 / 20 20 10 10 30
DENVER CITY 66 84 62 93 63 / 50 20 10 10 20
BROWNFIELD 66 84 62 93 65 / 50 20 10 10 20
CHILDRESS 68 87 64 91 64 / 20 10 0 10 30
SPUR 68 86 65 94 68 / 20 20 10 10 20
ASPERMONT 70 89 67 97 68 / 20 20 10 10 20
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
33
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
932 AM EDT SUN AUG 19 2012
.DISCUSSION...
...A FEW STRONG STORMS POSSIBLE AGAIN THIS AFTERNOON...
TODAY...MORNING SOUNDINGS SHOW ONLY A COUPLE OF MINOR DIFFERENCES
FROM YESTERDAY. ONE IS THE MEAN LOW LEVEL WIND FLOW WHICH IS
SLIGHTLY WEAKER. THE OTHER IS THE 700 MB TEMPERATURE WHICH IS
ABOUT A DEGREE AND A HALF WARMER.
THE LATEST RAP ANALYSIS SHOWS A WEAK VORT MAX NEAR THE WEST CENTRAL
FLORIDA COAST...BUT DEBRIS CLOUDINESS LOOKS MINIMAL.
WITH MOISTURE UNCHANGED FROM YESTERDAY...LITTLE INHIBITION OF
SURFACE HEATING AND DEEP LAYER WEST/SOUTHWEST FLOW...EXPECT
SHOWERS/STORMS TO MARCH RIGHT ON ACROSS THE PENINSULA AGAIN TODAY.
THE SLIGHTLY WARMER 700 MB TEMPERATURE AND SLIGHTLY WEAKER LOW LEVEL
FLOW SHOULD DELAY THIS PROGRESSION BY AN HOUR OR TWO COMPARED TO
SATURDAY.
MOS GUIDANCE AND THE MESOSCALE MODELS DO NOT SHOW AN EAST COAST SEA
BREEZE...BUT MID-LATE AFTERNOON LAKE/OUTFLOW BOUNDARY INTERACTIONS
WILL LIKELY PRODUCE ISOLATED STRONG STORMS. THE GREATEST CHANCE FOR
THIS SHOULD BE ALONG THE TREASURE COAST TO CAPE CANAVERAL.
DO NOT SEE ANYTHING SIGNIFICANT TO UPDATE IN THE FORECAST/GRIDS.
&&
.AVIATION...
TRENDS INDICATE THAT THE WEST TO EAST MARCH OF SHOWERS/STORMS ACROSS
THE PENINSULA WILL BE SLIGHTLY LATER THAN YESTERDAY...NEAR MIDDAY
KLEE...17-18Z KSFB-KMCO-KISM...18-19Z KDAB-KTIX AND 19-21Z
KMLB-KSUA. OUTSIDE THESE SHOWERS/STORMS IT WILL BE VFR EXCEPT FOR
BRIEF MVFR CEILINGS AS CUMULUS FORM THIS MORNING.
&&
.MARINE...
TODAY...SOUTHWEST FLOW POSING NO WIND WAVE PROBLEMS EXCEPT WELL
OFFSHORE WHERE FLOW A LITTLE OVER 10 KNOTS WILL CAUSE CHOPPY
CONDITIONS FOR SMALL CRAFT RETURNING TO SHORE. SCATTERED STORMS
MOVING OFFSHORE THIS AFTERNOON WILL BE CAPABLE OF PRODUCING
DANGEROUS CONDITIONS THOUGH...WITH FREQUENT LIGHTNING STRIKES AND
GUSTY WINDS TO AROUND 35 KNOTS. A COMPREHENSIVE OUTFLOW BOUNDARY
MAY AGAIN EVOLVE AND PUSH WELL OFFSHORE.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
FORECASTS...LASCODY
IMPACT WEATHER...WIMMER
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1008 AM EDT SUN AUG 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE STATE TODAY WHILE A COLD FRONT
BECOMES NEARLY STATIONARY OVER THE GULF OF MAINE. THE NEXT LOW
PRESSURE SYSTEM WILL MOVE ACROSS THE REGION MONDAY NIGHT INTO
TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
1005 AM UPDATE...HIGH PRESSURE WILL LINGER OVER THE REGION
TODAY, KEEPING LOTS OF SUNSHINE AROUND MUCH OF THE AREA. THE
EXCEPTION WILL BE COASTAL WASHINGTON COUNTY, WHERE CLOUDS
ASSOCIATED WITH A COLD FRONT JUST OFF THE COAST WILL REMAIN
THROUGH MUCH OF THE DAY. WE`RE ALSO SEEING SOME LIGHT RETURNS ON
RADAR NEAR EASPORT, SO HAVE ADDED MENTION OF SOME ISOLATED SHOWERS
TO TODAY`S FORECAST. ELSEWHERE, STARTING TO SEE SOME CUMULUS POP
UP ON SATELLITE SO HAVE ADJUSTED THE FORECAST TO MOSTLY SUNNY IN
MOST AREAS. NO OTHER CHANGES NEEDED WITH THIS UPDATE.
PREVIOUS DISCUSSION...A FRONTAL SYSTEM OFF THE DOWNEAST COAST
WILL DRIFT SLOWLY TO THE EAST OVER THE NEXT 24 HOURS AS WEAK HIGH
PRESSURE BUILDS IN FROM THE WEST. PRIMARY TASK IS TIMING OF EXIT
OF PRECIPITATION FROM DOWNEAST COAST. FOR POP GRIDS UNTIL 1200Z
WILL INITIALIZE WITH RUC13 WITH SOME MANUAL ADJUSTMENT THEN
TRANSITION TO A BLEND OF THE NAM12...GFS40...SREF AND ECMWF TO
INITIALIZE POP GRIDS. HAVE USED A BLEND OF THE NAM12 AND GMOS FOR
WINDS GRIDS. GMOS WAS USED FOR TEMPERATURE AND DEW POINT AND WILL
DECREASE MINIMUM TEMPERATURE TONIGHT WITH SEASONABLY COOL AIR MASS
IN PLACE. QPF GRIDS GENERATED WITH A BLEND OF THE
NAM80...SREF....GFS AND ECMWF.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
THE MAIN FOCUS WILL BE ON TUESDAY IN REGARDS TO AN APPROACHING
COLD FRONT FROM THE WEST AND LOW PRES MOVING ACROSS THE SOUTHERN
GULF OF MAINE.
MONDAY LOOKS TO BE A DRY AND PLEASANT DAY FOR THE MOST PART W/THE
EXCEPTION FOR A WEAK DISTURBANCE MOVING ACROSS THE REGION IN THE
AFTERNOON. THIS FEATURE COULD DELIVER A QUICK SHOWER TO THE WEST
AND NORTHWEST AREAS. ALL THE SHORT RANGE GUIDANCE INCLUDING THE
00Z ECMWF SHOWS SOME FORCING IN THE MID AND UPPER LEVELS BUT THE
BIGGEST INGREDIENT LACKING IS THE DEEP MOISTURE. THEREFORE, STAYED
W/20-30% POPS IN THE AFOREMENTIONED AREAS. ACCEPTED THE DAYCREW`S
MAXES OF UPPER 70S TO AROUND 80.
ANOTHER S/WV IN CONJUNCTION W/A WEAK COLD FRONT IS SHOWN BY THE
ECMWF/GFS AND CANADIAN GLOBAL TO MOVE ACROSS THE REGION BY TUESDAY
AFTERNOON. THE LATEST RUNS INCLUDING THE NAM HAVE BACKED OFF ON
PRECIP CHANCES AND AVAILABLE MOISTURE KEEPING THE PASSAGE DRY FOR
THE MOST PART. THE NAM IS THE MOST AGGRESSIVE W/THE MOISTURE AND
INSTABILITY WHILE THE GFS SHOWS MORE STABILITY. ATTM, THE DECISION
WAS TO KEEP IN LINE W/THE DAYCREW`S THINKING AND CONTINUE W/30-40%
POPS MAINLY ACROSS THE NORTH AND CENTRAL AREAS. TSTMS WERE ADDED
FOR TUESDAY AFTERNOON TAKING A BLEND OF THE NAM AND GFS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE WEAK COLD FRONT WILL SLIDE TO THE EAST TUESDAY NIGHT FOLLOWED
BY HIGH PRES FOR WEDNESDAY KEEPING CONDITIONS ON THE DRY AND
PLEASANT SIDE. HUNG ONTO THE DAYCREW`S MAX TEMPERATURES FOR
WEDNESDAY W/READINGS MAXING OUT IN THE LOW TO MID 70S.
THE 00Z RUN OF THE ECMWF AND GFS SHOW ANOTHER FRONTAL BOUNDARY
MOVING INTO THE CWA ON THURSDAY. SOME MID LEVEL FORCING IN THERE
BUT ONCE AGAIN DEEP MOISTURE IS LIMITED. THEREFORE, DECIDED ON
20-30% FOR THURSDAY AFTERNOON W/THE HIGHEST PERCENTAGES ACROSS THE
NORTHERN PART OF THE CWA. ATTM, KEPT THE MENTION OF THUNDER OUT OF
THE FCST AND WENT W/JUST SHOWERS. THE GFS QUICKLY MOVES THIS
FRONTAL BOUNDARY OFF TO THE EAST AND DRIES THINGS OUT FOR FRIDAY
WHILE THE LATEST RUN OF THE ECMWF KEEPS THE FRONT BACK LONGER AND
HAS ANOTHER AREA OF PRECIP SHOWING UP BY EARLY FRIDAY. THIS IS A
DIFFERENT SCENARIO THAN THE 12Z RUN WHICH WAS CLOSER TO THE 00Z
RUN OF THE GFS. THE 00Z RUN OF THE CANADIAN GLOBAL IS IN LINE
W/THE ECWMF. LOOKING AT THE SYNOPTIC PATTERN OF THE LONG WAVE TROF
HANGING ON ACROSS THE NE AND NO SIGNIFICANT MOISTURE AVAILABLE,
THINKING HERE IS THAT THE ECMWF AND CANADIAN COULD BE OVERDONE
W/THEIR QPF. THE DECISION WAS TO GO W/A DRY FCST FOR FRIDAY W/MAX
TEMPERATURES OF LOW TO MID 70S.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: VFR CONDITIONS EXPECTED NEXT 24 HOURS. SOME IFR/MVFR
KBHB EARLY THIS MORNING DUE TO CEILING.
SHORT TERM: SHOULD BE VFR PRETTY MUCH THROUGH THE PERIOD. A BRIEF
PERIOD OF MVFR CONDITIONS COULD BE SEEN ON TUESDAY W/THE PASSAGE
OF THE COLD FRONT.
&&
.MARINE...
NEAR TERM: HAVE USED A 50/50 BLEND OF THE NAM12 AND GFS40 TO
INITIALIZE GRIDS THEN LOWER WIND SPEED BY 20 PERCENT. FOR WAVES:
HAVE USE THE NAM/SWAN TO POPULATE GRIDS. PRIMARY SOURCE OF WAVES
IS 1 TO 2 FOOT LONGER PERIOD SWELL. BASED ON WNA SPECTRAL THIS
WAVE GROUP FROM SOUTHEAST AT 9 TO 11 SECONDS.
SHORT TERM: NO HEADLINES ANTICIPATED. THE MAIN FOCUS WILL BE THE
SE SWELL DEVELOPING AND HANGING ON THROUGH THE PERIOD. SUSTAINED
WINDS OF 10 KTS AND A SEA/SWELL STATE OF 2-3 FT W/A PERIOD OF 8-9
SECONDS.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HASTINGS/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...HASTINGS/MIGNONE
MARINE...HASTINGS/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
1017 AM EDT SUN AUG 19 2012
.SYNOPSIS...
HIGH PRESSURE WAS LOCATED OVER NEW YORK STATE TODAY...WHILE A
FRONTAL BOUNDARY WAS STALLED OUT SOUTH OF THE AREA. SURFACE LOW
PRESSURE WILL DEVELOP OVER THE CAROLINA PIEDMONT THIS AFTERNOON
AND MOVE NORTHEAST TO THE MID ATLANTIC COAST TONIGHT. HIGH
PRESSURE WILL SLOWLY BUILD OVER THE REGION DURING THE MIDDLE
PORTION OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
FRONTAL BOUNDARY WAS LOCATED TO THE SOUTH ACROSS NORTH CAROLINA
THIS MORNING...WHILE WEAK SURFACE HIGH PRESSURE WAS POSITIONED
OVER NEW YORK STATE. CWA WAS LOCATED IN A TRANSITION
ZONE...CHARACTERIZED BY INCREASING MOISTURE IN THE WAKE OF
YESTERDAY/S DRYING. WARM ADVECTION WAS UNDERWAY WELL NORTH OF THE
FRONTAL BOUNDARY...AND MODELS ALSO INDICATE ISENTROPIC LIFT
STRENGTHENING OVER THE CWA THROUGH THE DAY AND INTO THE NIGHT. LIFT
WILL LIKELY BE ENHANCED BY A MID-LEVEL WAVE OVER THE SOUTHERN
APPALACHIANS THAT MOVES EAST/NORTHEAST WITH TIME.
RESULT OF THESE FEATURES HAS BEEN FOR AN AREA OF SHOWERS TO MOVE
INTO THE POTOMAC HIGHLANDS/CENTRAL SHENANDOAH VALLEY EARLY THIS
MORNING. 12Z NAM THROUGH H24 IS COMING IN LINE...AND AGREES WITH
RECENT RUNS OF THE HRRR AND WRF-ARW. THESE MODELS SUGGEST SHOWERS
EXPANDING NORTHEAST THROUGH THE CWA THROUGH THE DAYTIME HOURS. 06Z
GFS IS NOT AS AGGRESSIVE THIS FAR NORTH BUT SUSPECT 12Z WILL ALSO
FOLLOW SUIT WITH THE NAM. POPS HAVE ALREADY BEEN INCREASED ACROSS
THE CWA...WITH TIMING DETAIL ALSO ADDED. ELEVATED INSTABILITY
COULD ALSO RESULT IN ISOLATED THUNDERSTORMS ESPECIALLY OVER THE
SOUTHERN PORTION OF THE CWA.
ANOTHER WAVE MAY KEEP CHANCES OF SHOWERS GOING WELL INTO THE
OVERNIGHT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
EXPECT PRECIP COVERAGE TO CONTRACT SOUTHWARD THIS EVENING AS THE SFC
LOW DEVELOPS AND BRINGS NELY FLOW IN FROM NJ. CHANCES OF CONTINUING
PRECIP OVER ZONES SOUTHEAST OF DC...BUT AGAIN THE COVERAGE AND
INTENSITY OF RAINFALL DEPENDS ON THE LOW TRACK. MIN TEMPS NEAR
NORMAL WITH NLY FLOW AND CLOUDS...MID TO UPR 50S WEST OF THE BLUE
RIDGE...LOW TO MID 60S EAST.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
LAST NGT I WROTE ABT THE DIFFERENCES IN THE MDL DEPICTION OF
MON..W/ THE NAM HAVG LOW POPS AND THE GFS HIGH. ONCE AGN THE MDLS
HV FLIPPED REGARDING POPS...W/ THE NAM BCMG THE HIGHER MDL -
FORMING A DEEPENING LOW PRES ALONG THE DELMARVA MON MRNG MUCH LK
IT WAS DOING TWO NGTS AGO. WL KEEP POPS IN THE LKLY RANGE MON FM
ABT 20 MILES W OF I-95 INTO THE BAY...CHC W OF THAT LN. ISOLD TSTMS
PSBL BUT NOT XPCTG A WIDESPREAD SVR OUTBRK. GIVEN LACK OF RAIN
LATELY AND TRANSITORY NATURE OF THE LOW DO NOT FEEL FLDG WL BE A PROBLEM.
THERE WL BE AN UPR TROF OVR THE RGN MON...LIFTING N ON TUE. THIS
WL ALLOW SF HIGH PRES TO BLD INTO THE RGN...GIVING THE MID ATLC A
DEFINITE LATE SUMMER FEEL. XPCT TO SEE PLNTY OF SUNSHINE...
ESPECIALLY WED-FRI...W/ DAYTIME HIGHS IN THE MU80S AND DWPTS IN
THE U50S/L60S. LOWS WL RANGE FM THE U50S IN THE HIGHLANDS TO THE
U60S IN THE CITIES AND ALONG THE BAY.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
SHOWERS ARE EXPECTED TO OVERSPREAD THE AREA FROM SOUTHWEST TO
NORTHEAST THROUGH THE DAY. SHOWERS HAVE ALREADY MADE IT TO
CHO...AND CHO MAY BE REDUCED TO IFR AT TIMES. CONFIDENCE IS LOW
FOR IFR AT REMAINING SITES...BUT A PERIOD OF MVFR VSBYS SEEMS
LIKELY THIS AFTERNOON. SECONDARY WAVE MAY KEEP SHOWERS GOING WELL
INTO THE NIGHT.
AT LEAST MVFR CIGS PSBL MON AT ALL THREE MAJOR AIRPORTS. FOG PSBL
MON NGT...THEN VFR CONDS MOST OF THE WK.
&&
.MARINE...
WEDGE OF HIGH PRESSURE CONTINUES LIGHT NELY/ELY FLOW OVER THE WATERS
THIS MORNING. LOW PRESSURE DEVELOPS OVER CNTRL NC/SC THIS
AFTERNOON...CROSSING SOUTH OF THE MD PORTION OF THE BAY LATE
TONIGHT. SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT BEGINNING
TONIGHT FOR MOST OF THE WATERS FOR NELY FLOW GUSTING TO AROUND 20
KT ON THE NORTH SIDE OF THE LOW.
JUST LK DURG THE PAST 2 NGTS...THERE IS DISCREPANCY AMONGST THE
MDLS REGARDING THE DVLPMNT AND POSN OF A SFC LOW TO FORM IN ASSO
W/ THE UPPER TROF SUN NGT AND MON. WHERE IT TRACKS WL DETERMINE
HOW MUCH PCPN WL FALL OVER THE WATERS...AND ALSO HOW STRONG THE
WINDS WL BE. WE`VE ISSUED A SMALL CRAFT ADVSRY PARTLY BECAUSE THE
NAM BUFKIT SNDG FOR NHK IS QUITE STRONG.
THERE IS THE PSBLTY THAT A SECONDARY LOW COLD FORM ON TUE B4 HIGH
PRES BLDS IN FOR MUCH OF THE REST OF THE WK...BUT THIS IS NOT FOR CERTAIN.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 2 PM EDT MONDAY FOR ANZ531-
532-539-540.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 2 PM EDT MONDAY
FOR ANZ533-534-536-537-541>543.
&&
$$
BPP/BAJ/WOODY!
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
739 AM EDT SUN AUG 19 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 507 AM EDT SUN AUG 19 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP TROF DOMINATING THE
ERN CONUS. TROF CONTINUES TO BE ANCHORED BY A MID/UPPER LEVEL
CYCLONE CENTERED IN THE VCNTY OF JAMES BAY...AND THE UPPER LAKES ARE
FIRMLY UNDER THE INFLUENCE OF THE TROF. ALTHOUGH SHORTWAVE AND
ASSOCIATED COLD FRONT PASSED YESTERDAY AFTN/EVENING...VARYING
AMOUNTS OF CLOUD COVER LINGER OVER UPPER MI EARLY THIS MORNING. OCNL
CLOUD COVER IS PROBABLY PREVENTING A MORE WIDESPREAD OR DENSE FOG
FROM DEVELOPING AS SEVERAL SITES HAVE HAD WIDELY FLUCTUATING VIS
DURING THE NIGHT.
WITH UPPER MI REMAINING FIRMLY UNDER THE INFLUENCE OF THE MID/UPPER
TROF TODAY AND TONIGHT...MAIN FCST ISSUE IS WHETHER ANY PCPN WILL
OCCUR. IN SUMMERTIME NW FLOW...EVEN THE SUBTLEST OF WAVES CAN
TRIGGER ISOLD/SCT CONVECTION. WHILE THERE ARE NO OBVIOUS SHORTWAVES
EVIDENT UPSTREAM IN NRN ONTARIO...THERE ARE HINTS OF ONE JUST N OF
LAKE SUPERIOR THAT IS ANALYZED BY THE LATEST RUC. THAT SUBTLE WAVE
IS PROBABLY RESPONSIBLE FOR THE RECENT EXPANSION OF CLOUDS OVER THE
FCST AREA AS WELL AS THE ISOLD SHRA THAT HAVE DEVELOPED FROM
ONTONAGON COUNTY N TO JUST OFFSHORE OF THE KEWEENAW PENINSULA. ONE
ASPECT THAT WILL BE WORKING AGAINST CONVECTION TODAY WILL BE THE
DRIER AIR MASS EVIDENT UPSTREAM IN NRN ONTARIO PER 00Z CWPL
SOUNDING. AS AN INDICATION OF THE DRIER AIR...THE K INDEX WAS 3. A
NICE SWATH OF CLEAR SKIES WAS ALSO EVIDENT ACROSS NRN ONTARIO TO THE
NW OF LAKE SUPERIOR YESTERDAY AFTN...AND SFC DWPTS WERE DOWN INTO
THE 30S IN THAT AREA. HOWEVER...WITH AFORMENTIONED SUBTLE WAVE
DRIFTING S...DEVELOPMENT OF LAKE BREEZE CONVERGENCE ZONE BTWN LAKE
SUPERIOR AND LAKE MI AND WITH MODELS DELAYING ARRIVAL OF THE DRIER
AIR UPSTREAM...A MENTION OF AT LEAST ISOLD SHRA APPEARS WARRANTED
FROM ROUGHLY NEAR KIMT E TO S OF KERY IN THE LAKE BREEZE CONVERGENCE
ZONE THIS AFTN. WILL ALSO NEED TO MONITOR TRENDS OVER THE NEXT FEW
HRS TO SEE IF CURRENT EXPANDING CLOUD COVER IS A PRECURSOR TO
MORNING SHRA DEVELOPMENT OVER A LARGER PORTION OF THE FCST AREA.
ANY SHRA NEAR LAKE MI WILL END EARLY THIS EVENING AS SHORTWAVE SLIPS
TO THE S. OTHERWISE...IT SHOULD BE A DRY NIGHT THOUGH THERE ARE
HINTS THAT ANOTHER WAVE MAY BE DROPPING INTO THE AREA OVERNIGHT.
WILL BE SOMETHING TO MONITOR FOR POSSIBLY ADDING SLIGHT CHC/ISOLD
SHRA IN LATER FCSTS. POTENTIAL CLOUD COVER WITH WEAK WAVE MAKES FOR
A CHALLENGING MIN TEMP FCST TONIGHT. AT THIS TIME...IT APPEARS CLOUD
COVER SHOULD BE LIMITED ENOUGH FOR AT LEAST THE FIRST PART OF THE
NIGHT TO FAVOR THE LOWER END OF AVBL GUIDANCE. SOME UPPER 30S WILL
BE POSSIBLE IN TRADITIONAL INTERIOR COLD SPOTS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 507 AM EDT SUN AUG 19 2012
GENERAL AGREEMENT IS PRESENT IN OVERALL UPPER AIR PATTERN THROUGH
THE UPCOMING WEEK. DEEP TROUGH OVER MOST OF EASTERN CANADA INTO THE
EASTERN CONUS /INCLUDING GREAT LAKES/ DE-AMPLIFIES BY WEDNESDAY. BY
THE MID-LATE WEEK...TROUGH OVER WESTERN CANADA INTO PACIFIC NORTHWEST
EJECTS A PIECE OF ENERGY INTO THE NORTHERN PLAINS. WHERE THAT WEAKER
TROUGH PROGRESSES IS A QUESTION AND WILL HAVE IMPACT ON FORECAST OVER
UPPER GREAT LAKES THURSDAY AND FRIDAY. FAIR TO SAY THAT AGREEMENT
FROM THE GFS/ECMWF/GEM-NHEM IS BETTER TO START THE WEEK THAN TO END
THE WEEK. MAIN ISSUE AT END OF WEEK IS HOW FAR EAST ENERGY OVER THE
NORTHERN PLAINS WILL MOVE INTO THE GREAT LAKES. GFS CONTINUES TO BE
DEEPER AND FARTHER EAST...RESULTING IN GOOD CHANCE OF PRECIPITATION
ON FRIDAY OVER UPPER MICHIGAN. ECWMF/EXTRAPOLATION OF GEM-NHEM WOULD
KEEP MAJORITY OF FORCING AND PRECIPITATION WITH THE WEAKER TROUGH
SOUTHWEST OF UPPER MICHIGAN INTO THE UPPER MISSISSIPPI RIVER VALLEY.
TO START THE LONG TERM...HAVE A SMALL SHOT AT ISOLD SHRA ON MONDAY
OVER CENTRAL CWA IN THE MID-LATE AFTERNOON AS LAST OF STRONGER
SHORTWAVES DROP SOUTH ON WESTERN PERIFERY OF LARGER SCALE UPPER
TROUGH. FORECAST SOUNDINGS FROM GFS AND NAM INDICATE MOISTURE OVER
THE CWA ONLY FOCUSES BETWEEN 800MB AND 700MB. DRY AIR BELOW LCL
IS QUITE DRY AS DAY BEGINS WITH DEWPOINTS IN THE 30S. PROBABLY WILL
ONLY SEE DEWPOINTS RISE INTO THE MID 40S AT BEST IN THE AFTERNOON AS
LOW-LEVEL MOISTURE ADVECTION IS LIMITED. SREF IDEA SHOWING QPF
FORMING OVER SCNTRL CWA AFTER 18Z IS LIKELY ON TRACK. COVERAGE OF ANY
SHRA WILL BE VERY ISOLATED DUE TO DRY LOW-LEVELS. NO TSRA INCLUDED
WITH POOR MID-LEVEL LAPSE RATES LESS THAN 6C/KM AND SBCAPE VALUES
ONLY UP TO 200 J/KG. MODELS HINT AT MID-LEVEL MOISTURE STICKING
AROUND OFF AND ON THROUGH MONDAY NIGHT BUT WITH SAME LIMITING FACTORS
AS MONDAY AFTERNOON DO NOT EXPECT MUCH IN WAY OF PRECIPITATION ON
MONDAY NIGHT.
COUPLE OF WEAKER SHORTWAVES RIPPLE THROUGH UPPER GREAT LAKES TUESDAY
BUT MOISTURE IS FORECAST TO BE EVEN SHALLOWER THAN ON MONDAY...AGAIN
CENTERED AROUND 800MB. ADDITIONAL MID-LEVEL MOISTURE COULD ROLL
ACROSS WITH SCT-BKN CLOUDS 15-20 KFT POSSIBLE. MIX OF CLOUDS AND
SUNSHINE GIVES WAY TO MORE SUNSHINE IN THE AFTERNOON...SO BASED ON
H85 TEMPS TOWARD AOA 12C EXPECT MAX TEMPS WELL INTO THE 70S FOR MOST
AREAS WITH EVEN A POTENTIAL OF SEEING SOME READINGS AROUND 80
DEGREES OVER WESTERN AND CENTRAL CWA.
LOOKING WELL TO THE NORTHWEST CURRENTLY THERE IS A PRETTY STRONG
SHORTWAVE CRESTING RIDGE OVER WESTERN CONUS INTO WESTERN CANADA.
WAVES IS OVER THE NORTHWEST TERRITORIES OF CANADA. MODELS SHOW WAVE
SPLITTING BUT ONE FORMIDABLE PIECE OF SHORTWAVE ENERGY IS FORECAST
TO DIG INTO NORTHWEST ONTARIO TUESDAY NIGHT INTO WEDNESDAY. GFS
FARTHER SOUTH WITH THE WAVE AND ASSOCIATED PRECIPITATION...BUT
ECMWF AND GEM-NHEM HAVE THE WAVE AS WELL...BUT NOT AS FAR SOUTH. NAM
APPEARS TOO FAST/WEAK WITH THE SHORTWAVE AND IS NOT PREFERRED. ALL
THE MODELS INDICATE AREA OF H85 TEMP AND H85-H7 MOISTURE ADVECTION
SETS UP JUST AHEAD OF THE WAVE AS IT DIGS TOWARD UPPER GREAT LAKES
TUESDAY NIGHT. USING BLEND OF LAST FEW GFS MODEL RUNS ALONG WITH
ECMWF/GEM-NHEM AND EVEN SOME OF THE SREF...KEPT POPS HIGHEST ON
TUESDAY NIGHT OVER NORTHERN SECTIONS OF LK SUPERIOR...AND NO REAL
POPS OVER LAND AREA OF UPPER MICHIGAN...ASIDE FROM ISLE ROYALE.
IDEA FITS SYNOPTIC PATTERN AS MOST LAND CWA WILL BE THE WITHIN THE
MORE UNFAVORABLE RIGHT EXIT REGION OF JET STREAK FOR PRECIPITATION.
KEPT SLIGHT CHANCES FOR WEDNESDAY OVER CENTRAL AND EAST AS LARGER
SCALE FORCING ALONG WITH WEAK SFC TROUGH COULD COMBINE WITH DAYTIME
HEATING TO HELP FORM SOME SHOWERS DURING THE PEAK HEATING OF THE DAY.
IN THE EXTENDED...00Z MODEL RUNS PROVIDE NO TRENDS OF NOTE ON EXTENT
OF LARGER SCALE TROUGHING OVER UPPER GREAT LAKES TO CLOSE THE WEEK.
GFS CONTINUES TO SHOVE UPPER TROUGH PUSHING INTO THE NORTHERN PLAINS
ON THURSDAY ON INTO THE UPPER GREAT LAKES ON FRIDAY. THE TROUGH ALONG
WITH INCREASING LOW-LEVEL MOISTURE ADVECTION AND PRESENCE OF SFC WARM
FRONT HELPS TO GENERATE PLENTY OF QPF FRIDAY INTO FRIDAY NIGHT. ON
THE FLIP SIDE THE LATEST ECMWF IS MORE SHUNTED TO THE SOUTHWEST WITH
THE UPPER TROUGH AND THUS BRINGS VERY LITTLE QPF INTO THE UPPER GREAT
LAKES WITH HIGH PRESSURE STAYING THE DOMINANT FEATURE. MAIN WARM
FRONT REMAINS WELL TO THE SOUTH OF CWA. LATEST CANADIAN LOOKS MORE
LIKE THE ECMWF BUT DOES TRY TO BRING SOME QPF INTO AT LEAST WESTERN
CWA ON FRIDAY. MODEL CONSENSUS INDICATES HIGHEST CHANCES FOR
PRECIPITATION FRIDAY INTO FRIDAY NIGHT...BUT THIS IS BEING BIASED
SOMEWHAT BY GFS MODEL ELEMENTS. WILL STAY WITH CONSENSUS GIVEN THE
STARK DIFFERENCES OFFERED UP BY ECMWF AND GFS...BUT CERTAINLY
POSSIBLE THAT FRIDAY MAY END UP MAINLY DRY COMPARED TO THE HIGHER
CHANCE POPS IN THIS FORECAST. DOES APPEAR THAT NEXT WEEKEND WOULD
FEATURE A DRYING TREND AS THE UPPER TROUGH DEPARTS THE AREA. TOUGH TO
GET TOO SPECIFIC ABOUT THOSE DETAILS THOUGH DUE TO THE MODEL
DIFFERENCES STILL AROUND LEADING INTO NEXT WEEKEND. TEMPERATURES
SHOULD SHOW WARMING TREND INTO NEXT WEEKEND AS H85 TEMPS STEADILY
CLIMB FROM WEDNESDAY TO SATURDAY. IF GFS IS CORRECT THOUGH...WARMING
WOULD BE TEMPERED THURSDAY AND DEFINITELY INTO FRIDAY WITH MORE
CLOUDS AND PRECIPITATION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 738 AM EDT SUN AUG 19 2012
ANOTHER DISTURBANCE DROPPING INTO THE UPPER LAKES IS GENERATING A
FEW -SHRA IN NW UPPER MI ATTM. BASED ON MOVEMENT...THE -SHRA MAY
AFFECT KSAW FOR AN HOUR OR TWO THIS MORNING. IT IS ANTICIPATED
CONDITIONS WILL REMAIN VFR IF A -SHRA DOES OCCUR. PCPN IS NOT
EXPECTED AT KCMX/KIWD. OTHERWISE...OTHER THAN SOME FOG AT KIWD WHICH
WILL DISSIPATE IN THE NEXT HR OR SO...VFR CONDITIONS WILL PREVAIL AT
KIWD/KCMX/KSAW THRU THIS FCST PERIOD. HOWEVER...WILL NEED TO WATCH
FOR POSSIBLE FOG DEVELOPMENT TONIGHT AT KIWD/KSAW...BUT MAINLY AT
KIWD AS THAT SITE HAS BEEN PRONE TO SHALLOW FOG AND WIDELY
FLUCTUATING VIS ON A NIGHTLY BASIS RECENTLY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 507 AM EDT SUN AUG 19 2012
BRIEFLY TIGHTER PRESSURE GRADIENT WILL ALLOW NORTHWEST WIND GUSTS
TO REACH 20-25 KTS OVER EASTERN SECTIONS OF LK SUPERIOR THIS
AFTERNOON INTO THIS EVENING. WINDS DIMINISH OVERNIGHT TONIGHT AND
REMAIN MAINLY BELOW 20 KTS THROUGH WEDNESDAY AS HIGH PRESSURE STAYS
CLOSE BY. EXCEPTION COULD BE TUESDAY AFTERNOON AND EVENING OVER
WESTERN SECTIONS WITH SOUTHWEST WIND GUSTS PUSHING ABOVE 20 KTS IN
THE VICINITY OF ISLE ROYALE. LOW PRESSURE SYSTEM APPROACHING LATE
THIS WEEK RESULTS IN WINDS BECOMING MORE EAST TO SOUTHEAST AND
INCREASING OVER 20 KTS. WINDS MAY END UP HIGHER DEPENDING ON
ULTIMATE TRACK AND STRENGTH OF SURFACE LOW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...JLA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
629 AM CDT SUN AUG 19 2012
.UPDATE...FOR 12Z AVIATION DISCUSSION BELOW
&&
.DISCUSSION.../ISSUED 350 AM CDT SUN AUG 19 2012/
RATHER AMPLIFIED UPPER AIR PATTERN REMAINS IN PLACE THIS
MORNING...WITH SHARP UPPER RIDGE UP THE ROCKY MOUNTAINS FLANKED
BY A DEEP CLOSED LOW NEAR HUDSON BAY AND A LONGWAVE TROUGH OVER
THE NERN PAC. WITHIN THE NNW FLOW OVERHEAD...WATER VAPOR IMAGERY
AND RAP PV ANALYSIS SHOWS A POTENT WAVE DROPPING INTO CENTRAL MN
AT 8Z. AT THE SFC...HIGH PRESSURE WAS PARKED ACROSS MUCH OF THE
GREAT PLAINS WITH A WEAK FRONT/WIND SHIFT STILL EVIDENT IN THE FLOW
FROM MADISON...MN ACROSS THE TWIN CITIES AND OVER TOWARD GREEN
BAY.
ALOFT...PATTERN WILL UNDERGO A SLOW DE-AMPLIFICATION OVER THE
COMING DAYS. BY THE MIDDLE OF NEXT WEEK...WEAK ZONAL FLOW WILL BE
IN PLACE ACROSS MUCH OF THE CONUS AS ROCKIES RIDGE FLATTENS
OUT...THE HUDSON LOW FILLS/LIFTS NE AND THE PAC TROUGH MOVES INTO
BC AND UNDERGOES SOME DEEPENING. MEDIUM RANGE MODELS DO NOT BRING
THE WRN WAVE ACROSS THE CENTER OF THE CONTINENT UNTIL NEXT
WEEKEND.
AT THE SFC...FRONT SPLITTING THE MPX CWA NEARLY IN HALF THIS
MORNING WILL SLOWLY WASH OUT DURING THE DAY AS HIGH PRESSURE ACROSS
THE DAKOTAS PUSHES EAST. THIS HIGH PRESSURE WILL THEN SLOWLY TRACK
ACROSS THE UPPER MS VALLEY THROUGH TUESDAY NIGHT. WEDNESDAY...A
WEAK FRONTAL BOUNDARY WILL TRY TO SAG INTO THE LAKE SUPERIOR
REGION AS A LEE THROUGH SLOWLY TAKES SHAPE ACROSS THE HIGH PLAINS AS
UPPER FLOW BECOMES MORE ZONAL. THE FIRST FRONTAL PUSH FROM THIS
LEE TROUGHING LOOKS TO TRY AND PUSH INTO THE MPX AREA
THU/FRI...WITH A MORE SIGNIFICANT FRONT NOT LIKELY TO ARRIVE UNTIL
NEXT WEEKEND WITH THE STRONGER UPPER FORCING.
FOR TODAY THERE ARE TWO CONCERNS THANKS TO SHORTWAVE NOW IN
CENTRAL MN. FIRST IS HOW FAR NORTH TO KEEP POPS TODAY...WHILE THE
SECOND IS WHAT IMPACT WILL CLOUDS HAVE ON MAX TEMPS. FOR
PRECIP...TRIED LIMITING MENTIONABLE PRECIP TO WHERE MODELS SHOW
K-INDEX EXCEEDING 28. GOING BACK TO YESTERDAY...THIS MATCHED UP
FAIRLY WELL WITH WHERE SHOWERS/STORMS WERE ABLE TO FIRE OFF.
THOUGH MODELS DIFFER ON HOW QUICKLY THE H7 THROUGH/MOISTURE MAKE
IT THROUGH THE REGION...THEY ARE ALL FAIRLY SIMILAR WITH THEIR
K-INDEX FORECASTS...WHICH MATCHES UP WELL WITH 19.03 SREF PROBS.
HAVE HIGHEST POPS ACROSS SOUTH CENTRAL MN THIS MORNING...WITH ISO
STORMS LINGERING INTO THE AFTERNOON ALONG I-90. HOWEVER...THERE
IS SUPPORT FROM THE 19.00 ECMWF/GFS ALONG WITH HRRR REFLECTIVITY
FORECASTS FOR HAVE POPS FARTHER NORTH THAN CURRENTLY INDICATED FOR
TODAY. IF THE GFS/ECMWF ENDS UP BEING THE ROUTE THINGS TAKE FOR
TODAY...THEN IT WILL LIKELY END BEING MOSTLY CLOUDY ACROSS SOUTH
CENTRAL MN...WHERE HIGHS COULD END UP SEVERAL DEGREES COOLER THAN
CURRENTLY INDICATED.
PRECIP WILL QUICKLY CUT OFF THIS EVENING...WITH SKIES BECOMING
CLEAR. THIS WILL SET THE STAGE FOR RATHER TRANQUIL WEATHER FOR
SUNDAY THROUGH WEDNESDAY AS THE SFC HIGH SLOWLY SLIDES EAST. WITH
H5 HEIGHTS AND H85 TEMPS SLOWLY BUILDING DURING THIS PERIOD...WILL
SEE HIGHS TICK UP A COUPLE OF DEGREES EACH DAY. BY WEDNESDAY...THE
RETURN OF SOUTHERLY FLOW WILL HELP BOAST TEMPS BACK INTO THE
LOWER 80S...ALONG WITH SENDING DEWPS BACK INTO THE 60S.
FOR WEDNESDAY NIGHT THROUGH FRIDAY...UNCERTAINTY IN THE FORECAST
INCREASES QUITE A BIT. THOUGH THE MEDIUM RANGE MODELS GENERALLY
AGREE ON WEAK ZONAL FLOW SETTING UP ACROSS THE NRN CONUS THIS
PERIOD...THEY DIFFER ON THE HANDLING OF A SHORT WAVE PEGGED TO
MOVE THROUGH THIS FLOW FROM THURSDAY INTO FRIDAY. THE GFS
CONTINUES TO BE THE MOST AGGRESSIVE WITH THE WAVE...BRINGING A
NEGATIVELY TILTED SHORTWAVE AND ASSOCIATED COLD FRONT ACROSS THE
AREA THURSDAY NIGHT INTO FRIDAY. THE ECMWF SHOWS A MUCH
WEAKER/SLOWER WAVE WORKING INTO THE PLAINS...WITH VERY LITTLE IN
THE WAY OF PRECIP WORKING INTO THE AREA UNTIL THE WEEKEND FRONT.
FOR THIS PERIOD...FOLLOWED THE BLEND APPROACH WITH THE CONTINUED
MENTION OF 40-50 POPS THURSDAY NIGHT. HARD TO SAY WHICH WAY THINGS
MAY GO AT THIS POINT...BUT IT DOES APPEAR THE GFS IS SUFFERING
FROM SOME CONVECTIVE FEEDBACK WHICH IS LIKELY IMPACTING THE
STRENGTH OF SFC FEATURES IT SHOWS.
&&
.AVIATION.../12Z TAF ISSUANCE/
THE MID LEVEL CLOUD DECK CONTINUES TO EXPAND ACROSS THE AREA THIS
MORNING...AND HAS HELPED INHIBIT DENSE FOG FROM FORMING. THE MVFR
VSBYS AT KRNH AND KEAU HAVE ALSO SUBSIDED FOR THE MOST PART.
MEANWHILE...SCATTERED SPRINKLES ARE EVIDENT ON CURRENT RADAR
IMAGERY IN ASSOCIATION WITH WEAK SHORTWAVE ENERGY OVERHEAD...BUT
COVERAGE DOESN/T WARRANT A MENTION IN THE TAFS...AND NO ATTENDANT
CIG/VSBY REDUCTIONS WILL OCCUR. SCT-BKN CUMULUS CLOUDS WILL BE
POSSIBLE INTO THE AFTERNOONN HOURS...WITH EVENTUAL CLEARING AFTER
00Z. NORTHERLY WINDS AT 5-9 KTS WILL PREVAIL THROUGH THIS
AFTERNOON...AND THEN LIGHT AND VARIABLE WINDS WILL DEVELOP AFTER
0Z.
KMSP...SCT-BKN MID LEVEL DECK TO START THE PERIOD...WITH CU FIELD
DEVELOPING BY 15Z. CLEARING SKIES AFTER 00Z. NORTHERLY WINDS AT
5-8 KTS THROUGH THIS AFTERNOON...FOLLOWED BY A DECREASE TO BELOW 5
KTS.
/OUTLOOK FOR KMSP/
MON...VFR. NORTHWEST 5 TO 10 MPH.
TUE...VFR. SOUTHWEST 5 TO 10 MPH.
WED...VFR. SOUTH 5 TO 10 MPH.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
LRS/MPG
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1013 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF DISTURBANCES ALOFT PASSING TODAY INTO TUESDAY. THE DEEPER
MOISTURE FOR THESE FEATURES TO TAP...MAINLY FROM MOUNTAINS ON EAST.
WEAK HIGH PRESSURE FOR WEDNESDAY THROUGH THE END OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
1000AM UPDATE...
AREA OF RAIN WITH DISTURBANCE ABOUT READY TO BE EXODUS FROM
POCAHONTAS AND EASTERN RANDOLPH...WITHIN THE NEXT HR OR SO.
IN ITS WAKE THE LOW CLDS HAVE MANAGED TO MIX OUT THIS MORNING WITH
SOME HEATING...ALLOWING FOR QUITE A BIT OF SUN ACROSS SE OH INTO
WESTERN WV. THIS WILL TEND TO FILL BACK IN...ACROSS WESTERN WV...NEXT
FEW HRS...AS MORE CLDS STREAM NE FROM EASTERN KY. NEAR TERM MDLS
SHOW SOME AFTN SHRA/TSRA DEVELOPMENT ACROSS THE MTNS BACK TO
CENTRAL PORTIONS OF WV...AIDED BY SOME HEATING AND LINGERING MOISTURE. THUS
WILL PUT SOME CHC POPS IN THIS AFTN CENTRAL/NORTHERN WV LOWLANDS
INTO NORTHERN MTNS. ALSO HAVE SOME CHC POPS ACROSS PORTIONS OF SE
OH LATE CLOSER TO UPR TROF.
PREVIOUS DISCUSSION BELOW...
BROAD MID/UPPER LEVEL TROF HERE FOR SEVERAL DAYS.
BASING FORECAST ON A STRONGER LEADING 500 MB VORT MAX PASSING FROM
SOUTHWEST TO NORTHEAST 12Z TO 16Z...EXITING THE NRN WV MOUNTAINS
AROUND 17Z. SO WILL BE FASTER IN INCREASING CLOUDS AND POPS EARLY
THIS MORNING OVER THE MOUNTAINOUS COUNTIES...PEAKING IN POCAHONTAS
COUNTY AROUND 14/15Z. DID NOT MENTION THUNDER. AS A RESULT OF THE
THICKENING AND LOWERING CLOUDS...REDUCE ANY THICK VALLEY FOG.
ONCE THAT FEATURE EXITS...HARD TO DETERMINE IF ANY SHOWERS DEVELOP
FURTHER WEST...ACROSS THE LOWLANDS DURING THE AFTERNOON AND
EVENING. SOME OF THE NEAR TERM MODELS...LIKE THE HRRR AND WRF-NMM
ARE DEVELOPING SHOWERS...MAYBE RELATED THE THE LOW LEVEL DEW POINT
GRADIENT BEING SHOVED BACK NORTHWEST TODAY. WILL TRY TO KEEP MOST
POPS IN WAKE OF THIS MORNINGS FEATURE...IN THE 20 OR LESS
CATEGORY...THINKING THE MAXIMUM IN MOISTURE IN THE OHIO VALLEY WILL
MOVE INTO NORTHERN HALF OF OHIO BY LATE THIS AFTERNOON...NOT THE
SOUTHERN COUNTIES.
00Z NAM WAS FASTER THAN THE 00Z GFS IN REDUCING MEAN RELATIVE
HUMIDITY IN THE COLUMN TONIGHT. FOR NOW...DO NOT SEE ANY REASON TO
ADJUST OUR 20/SLIGHT CHANCE POPS.
ALSO...DEPENDING ON THE RAIN TODAY...VALLEY FOG MAY HAVE TO BE
INSERTED FOR 06Z TO 12Z MONDAY...BUT A BIT PREMATURE AT THIS TIME.
COULD NOT HOLD MAXIMUM TEMPERATURES DOWN TOO MUCH TODAY...SINCE
HAVING THE MAIN SUPPORT EXITING BEFORE 18Z.
&&
.SHORT TERM /MONDAY/...
MODELS CONTINUE TO INDICATE 500MB TROUGH APPROACHING REGION HEADED
INTO SHORT TERM...WITH SEVERAL IMPULSES LIFTING THROUGH DURING THE
FIRST HALF OF THE WEEK. THE BEST MOISTURE IS GENERALLY IN THE WV
MOUNTAINS AND TO THE SOUTH EAST AND IT LOOKS LIKE THE MAIN SURFACE
LOW SHOULD ALSO STAY SOUTH EAST...SO KEPT HIGHEST POPS IN THE
MOUNTAINS DURING THE AFTERNOONS. MONDAY LOOKS LIKE THE DAY FOR THE
MOST COVERAGE OF PRECIP...AND HAVE CHANCE POPS FROM MOUNTAINS BACK
TO ABOUT THE OHIO RIVER...WITH SLIGHT CHANCE POPS INTO SE OHIO. POPS
LINGER INTO MONDAY NIGHT AS MODELS SHOW MOISTURE REMAINING WITH A
LITTLE RIPPLE ALOFT. SOME DIFFERENCES IN PLACEMENT BETWEEN
MODELS...BUT IN GENERAL SHOWING ANOTHER WEAK SHORTWAVE MOVING
THROUGH FOR TUESDAY AFTERNOON. BEST MOISTURE IS PROGGED TO BE
FARTHER EAST THAN ON MONDAY...SO KEPT CHANCE POPS MORE CLOSELY TIED
TO MOUNTAINS. MODELS SHOW RISING HEIGHTS HEADED INTO TUESDAY...AND
PUSH BEST MOISTURE EVEN FATHER EAST...SO LOOKS LIKE A DRIER DAY WITH
MAYBE JUST AN ISOLATED SHOWER IN MOUNTAINS.
ONLY MINIMAL CHANGES TO TEMPS THIS PACKAGE...STILL LOOKS LIKE A
GRADUAL WARMING TREND INTO MIDWEEK WITH NEAR NORMAL TEMPERATURES BY
WEDNESDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
USED A BLEND OF THE GFS AND ECMWF FOR WEDNESDAY THROUGH FRIDAY. THIS
LEAVES A WEAK HIGH PRESSURE SYSTEM OVER THE REGION...BUT POSSIBLY
ENOUGH MOISTURE TO FIRE SOME AFTERNOON SHOWERS/THUNDERSTORMS IN THE
MOUNTAINS. BY SATURDAY...SWITCHED TO A BLEND OF THE ECMWF AND GEFS
MEAN.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
WAS JUST A BIT FASTER WITH THE INCREASING MOISTURE MOVING UP THE
EASTERN SLOPES FOR THIS MORNING. AS A RESULT...NO THICK FOG SHOULD
BE SEEN AT DAWN.
THE 500 MB VORT MAX PASSES AROUND 15Z TO 16Z. BKW TO EKN CORRIDOR
SHOULD BE ALONG THE WESTERN EDGE OF THE MAIN SHOWER SHIELD
ASSOCIATED WITH THIS WAVE. THUNDER POSSIBLE NEAR THE VIRGINIA
BORDER. HAVE POPS PEAKING BY 14Z/15Z AROUND POCAHONTAS
COUNTY...BEFORE LOWERING AGAIN DURING THE 16Z TO 21Z PERIOD. HAVE
CEILINGS LOWERING AROUND 12Z ALONG THE EASTERN SLOPES INTO THE 2 TO
3 THSD FT BKN RANGE AND VSBY AROUND 5 MILES IN ANY RAIN SHOWERS.
FURTHER WEST HAVE MID DECK AROUND 10 THSD FT BEFORE SOME 4 TO 6 THSD
FT CEILINGS DEVELOPING BETWEEN 12Z TO 18Z.
ONCE THAT SUPPORT EXITS...DO NOT HAVE A GOOD HANDLE ON THE AMOUNT
AND HEIGHTS OF THE CLOUDS FOR LATE THIS AFTERNOON INTO THIS
EVENING...SAY 18Z TO 06Z. WILL LEAVE A SLIGHT CHANCE OF SHOWERS IN
FOR MANY AREAS...WITH WEAKER DISTURBANCES ALOFT...COMPARED TO THE
ONE THIS MORNING. VISIBILITY IN THE MOUNTAIN VALLEYS WILL LIKELY
DEPEND ON ANY RAIN TODAY...SO WILL HAVE TO BE FINE TUNED LATER
TODAY. THE MEDIUM CONFIDENCE MAINLY HAS TO DO WITH THESE
UNCERTAINTIES FOR LATE TODAY AND OVERNIGHT TONIGHT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG MAY BE MORE WIDESPREAD 06Z TO 12Z MONDAY IF
THE RAIN TODAY AFFECTS A WIDER AREA.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 12Z MONDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...KTB/30
SHORT TERM...MZ
LONG TERM...RPY
AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
816 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF DISTURBANCES ALOFT PASSING TODAY INTO TUESDAY. THE DEEPER
MOISTURE FOR THESE FEATURES TO TAP...MAINLY FROM MOUNTAINS ON EAST.
WEAK HIGH PRESSURE FOR WEDNESDAY THROUGH THE END OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
800AM UPDATE...
SENT OUT AN UPDATE RAISING SKY GRIDS SIGNIFICANTLY THIS MORNING ACROSS
THE BOARD...WITH AN ABUNDANCE OF MID AND HI CLDS OVER THE AREA.
ALSO RAISED POPS WELL INTO CATEGORICAL ACROSS EASTERN SLOPES IN S
MTNS AND UP INTO POCAHONTAS...INSERTING RA INSTEAD OF SHRA WITH
SOME SCHC THUNDER AS WELL. MDLS ARE HAVING MAJOR STRUGGLES WITH
THE SPEED OF THIS SYS. BACK EDGE OF CLDS MOVING ENE ACROSS CENTRAL
KY ATTM AS DRY SLOT MARCHES STEADILY E. MUCH OF THE DEEPER MOISTURE
APPEARS TO BE ACROSS CENTRAL WV AND SHIFTING E. HAVE TIMED BACK EDGE
OF CLDS TO ENTER WESTERN FLANK 15-16Z WITH IMPROVING SKY
CONDITIONS...IF NOT SOONER AS SOME OF THE LINGERING MOISTURE ARND
H85 MAY TRY TO SCT OUT SOME. MAY SEE SOME SHRA/TSRA LIGHT UP ACROSS
CENTRAL WV THIS AFTN NEAR LLVL MOISTURE GRADIENT. NO OTHER CHANGES
ATTM.
PREVIOUS DISCUSSION BELOW...
BROAD MID/UPPER LEVEL TROF HERE FOR SEVERAL DAYS.
BASING FORECAST ON A STRONGER LEADING 500 MB VORT MAX PASSING FROM
SOUTHWEST TO NORTHEAST 12Z TO 16Z...EXITING THE NRN WV MOUNTAINS
AROUND 17Z. SO WILL BE FASTER IN INCREASING CLOUDS AND POPS EARLY
THIS MORNING OVER THE MOUNTAINOUS COUNTIES...PEAKING IN POCAHONTAS
COUNTY AROUND 14/15Z. DID NOT MENTION THUNDER. AS A RESULT OF THE
THICKENING AND LOWERING CLOUDS...REDUCE ANY THICK VALLEY FOG.
ONCE THAT FEATURE EXITS...HARD TO DETERMINE IF ANY SHOWERS DEVELOP
FURTHER WEST...ACROSS THE LOWLANDS DURING THE AFTERNOON AND
EVENING. SOME OF THE NEAR TERM MODELS...LIKE THE HRRR AND WRF-NMM
ARE DEVELOPING SHOWERS...MAYBE RELATED THE THE LOW LEVEL DEW POINT
GRADIENT BEING SHOVED BACK NORTHWEST TODAY. WILL TRY TO KEEP MOST
POPS IN WAKE OF THIS MORNINGS FEATURE...IN THE 20 OR LESS
CATEGORY...THINKING THE MAXIMUM IN MOISTURE IN THE OHIO VALLEY WILL
MOVE INTO NORTHERN HALF OF OHIO BY LATE THIS AFTERNOON...NOT THE
SOUTHERN COUNTIES.
00Z NAM WAS FASTER THAN THE 00Z GFS IN REDUCING MEAN RELATIVE
HUMIDITY IN THE COLUMN TONIGHT. FOR NOW...DO NOT SEE ANY REASON TO
ADJUST OUR 20/SLIGHT CHANCE POPS.
ALSO...DEPENDING ON THE RAIN TODAY...VALLEY FOG MAY HAVE TO BE
INSERTED FOR 06Z TO 12Z MONDAY...BUT A BIT PREMATURE AT THIS TIME.
COULD NOT HOLD MAXIMUM TEMPERATURES DOWN TOO MUCH TODAY...SINCE
HAVING THE MAIN SUPPORT EXITING BEFORE 18Z.
&&
.SHORT TERM /MONDAY/...
MODELS CONTINUE TO INDICATE 500MB TROUGH APPROACHING REGION HEADED
INTO SHORT TERM...WITH SEVERAL IMPULSES LIFTING THROUGH DURING THE
FIRST HALF OF THE WEEK. THE BEST MOISTURE IS GENERALLY IN THE WV
MOUNTAINS AND TO THE SOUTH EAST AND IT LOOKS LIKE THE MAIN SURFACE
LOW SHOULD ALSO STAY SOUTH EAST...SO KEPT HIGHEST POPS IN THE
MOUNTAINS DURING THE AFTERNOONS. MONDAY LOOKS LIKE THE DAY FOR THE
MOST COVERAGE OF PRECIP...AND HAVE CHANCE POPS FROM MOUNTAINS BACK
TO ABOUT THE OHIO RIVER...WITH SLIGHT CHANCE POPS INTO SE OHIO. POPS
LINGER INTO MONDAY NIGHT AS MODELS SHOW MOISTURE REMAINING WITH A
LITTLE RIPPLE ALOFT. SOME DIFFERENCES IN PLACEMENT BETWEEN
MODELS...BUT IN GENERAL SHOWING ANOTHER WEAK SHORTWAVE MOVING
THROUGH FOR TUESDAY AFTERNOON. BEST MOISTURE IS PROGGED TO BE
FARTHER EAST THAN ON MONDAY...SO KEPT CHANCE POPS MORE CLOSELY TIED
TO MOUNTAINS. MODELS SHOW RISING HEIGHTS HEADED INTO TUESDAY...AND
PUSH BEST MOISTURE EVEN FATHER EAST...SO LOOKS LIKE A DRIER DAY WITH
MAYBE JUST AN ISOLATED SHOWER IN MOUNTAINS.
ONLY MINIMAL CHANGES TO TEMPS THIS PACKAGE...STILL LOOKS LIKE A
GRADUAL WARMING TREND INTO MIDWEEK WITH NEAR NORMAL TEMPERATURES BY
WEDNESDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
USED A BLEND OF THE GFS AND ECMWF FOR WEDNESDAY THROUGH FRIDAY. THIS
LEAVES A WEAK HIGH PRESSURE SYSTEM OVER THE REGION...BUT POSSIBLY
ENOUGH MOISTURE TO FIRE SOME AFTERNOON SHOWERS/THUNDERSTORMS IN THE
MOUNTAINS. BY SATURDAY...SWITCHED TO A BLEND OF THE ECMWF AND GEFS
MEAN.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
WAS JUST A BIT FASTER WITH THE INCREASING MOISTURE MOVING UP THE
EASTERN SLOPES FOR THIS MORNING. AS A RESULT...NO THICK FOG SHOULD
BE SEEN AT DAWN.
THE 500 MB VORT MAX PASSES AROUND 15Z TO 16Z. BKW TO EKN CORRIDOR
SHOULD BE ALONG THE WESTERN EDGE OF THE MAIN SHOWER SHIELD
ASSOCIATED WITH THIS WAVE. THUNDER POSSIBLE NEAR THE VIRGINIA
BORDER. HAVE POPS PEAKING BY 14Z/15Z AROUND POCAHONTAS
COUNTY...BEFORE LOWERING AGAIN DURING THE 16Z TO 21Z PERIOD. HAVE
CEILINGS LOWERING AROUND 12Z ALONG THE EASTERN SLOPES INTO THE 2 TO
3 THSD FT BKN RANGE AND VSBY AROUND 5 MILES IN ANY RAIN SHOWERS.
FURTHER WEST HAVE MID DECK AROUND 10 THSD FT BEFORE SOME 4 TO 6 THSD
FT CEILINGS DEVELOPING BETWEEN 12Z TO 18Z.
ONCE THAT SUPPORT EXITS...DO NOT HAVE A GOOD HANDLE ON THE AMOUNT
AND HEIGHTS OF THE CLOUDS FOR LATE THIS AFTERNOON INTO THIS
EVENING...SAY 18Z TO 06Z. WILL LEAVE A SLIGHT CHANCE OF SHOWERS IN
FOR MANY AREAS...WITH WEAKER DISTURBANCES ALOFT...COMPARED TO THE
ONE THIS MORNING. VISIBILITY IN THE MOUNTAIN VALLEYS WILL LIKELY
DEPEND ON ANY RAIN TODAY...SO WILL HAVE TO BE FINE TUNED LATER
TODAY. THE MEDIUM CONFIDENCE MAINLY HAS TO DO WITH THESE
UNCERTAINTIES FOR LATE TODAY AND OVERNIGHT TONIGHT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG MAY BE MORE WIDESPREAD 06Z TO 12Z MONDAY IF
THE RAIN TODAY AFFECTS A WIDER AREA.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY M H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY M H H H H H H H H H H H
AFTER 12Z MONDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...KTB/30
SHORT TERM...MZ
LONG TERM...RPY
AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
607 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF DISTURBANCES ALOFT PASSING TODAY INTO TUESDAY. THE DEEPER
MOISTURE FOR THESE FEATURES TO TAP...MAINLY FROM MOUNTAINS ON EAST.
WEAK HIGH PRESSURE FOR WEDNESDAY THROUGH THE END OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
BROAD MID/UPPER LEVEL TROF HERE FOR SEVERAL DAYS.
BASING FORECAST ON A STRONGER LEADING 500 MB VORT MAX PASSING FROM
SOUTHWEST TO NORTHEAST 12Z TO 16Z...EXITING THE NRN WV MOUNTAINS
AROUND 17Z. SO WILL BE FASTER IN INCREASING CLOUDS AND POPS EARLY
THIS MORNING OVER THE MOUNTAINOUS COUNTIES...PEAKING IN POCAHONTAS
COUNTY AROUND 14/15Z. DID NOT MENTION THUNDER. AS A RESULT OF THE
THICKENING AND LOWERING CLOUDS...REDUCE ANY THICK VALLEY FOG.
ONCE THAT FEATURE EXITS...HARD TO DETERMINE IF ANY SHOWERS DEVELOP
FURTHER WEST...ACROSS THE LOWLANDS DURING THE AFTERNOON AND
EVENING. SOME OF THE NEAR TERM MODELS...LIKE THE HRRR AND WRF-NMM
ARE DEVELOPING SHOWERS...MAYBE RELATED THE THE LOW LEVEL DEW POINT
GRADIENT BEING SHOVED BACK NORTHWEST TODAY. WILL TRY TO KEEP MOST
POPS IN WAKE OF THIS MORNINGS FEATURE...IN THE 20 OR LESS
CATEGORY...THINKING THE MAXIMUM IN MOISTURE IN THE OHIO VALLEY WILL
MOVE INTO NORTHERN HALF OF OHIO BY LATE THIS AFTERNOON...NOT THE
SOUTHERN COUNTIES.
00Z NAM WAS FASTER THAN THE 00Z GFS IN REDUCING MEAN RELATIVE
HUMIDITY IN THE COLUMN TONIGHT. FOR NOW...DO NOT SEE ANY REASON TO
ADJUST OUR 20/SLIGHT CHANCE POPS.
ALSO...DEPENDING ON THE RAIN TODAY...VALLEY FOG MAY HAVE TO BE
INSERTED FOR 06Z TO 12Z MONDAY...BUT A BIT PREMATURE AT THIS TIME.
COULD NOT HOLD MAXIMUM TEMPERATURES DOWN TOO MUCH TODAY...SINCE
HAVING THE MAIN SUPPORT EXITING BEFORE 18Z.
&&
.SHORT TERM /MONDAY/...
MODELS CONTINUE TO INDICATE 500MB TROUGH APPROACHING REGION HEADED
INTO SHORT TERM...WITH SEVERAL IMPULSES LIFTING THROUGH DURING THE
FIRST HALF OF THE WEEK. THE BEST MOISTURE IS GENERALLY IN THE WV
MOUNTAINS AND TO THE SOUTH EAST AND IT LOOKS LIKE THE MAIN SURFACE
LOW SHOULD ALSO STAY SOUTH EAST...SO KEPT HIGHEST POPS IN THE
MOUNTAINS DURING THE AFTERNOONS. MONDAY LOOKS LIKE THE DAY FOR THE
MOST COVERAGE OF PRECIP...AND HAVE CHANCE POPS FROM MOUNTAINS BACK
TO ABOUT THE OHIO RIVER...WITH SLIGHT CHANCE POPS INTO SE OHIO. POPS
LINGER INTO MONDAY NIGHT AS MODELS SHOW MOISTURE REMAINING WITH A
LITTLE RIPPLE ALOFT. SOME DIFFERENCES IN PLACEMENT BETWEEN
MODELS...BUT IN GENERAL SHOWING ANOTHER WEAK SHORTWAVE MOVING
THROUGH FOR TUESDAY AFTERNOON. BEST MOISTURE IS PROGGED TO BE
FARTHER EAST THAN ON MONDAY...SO KEPT CHANCE POPS MORE CLOSELY TIED
TO MOUNTAINS. MODELS SHOW RISING HEIGHTS HEADED INTO TUESDAY...AND
PUSH BEST MOISTURE EVEN FATHER EAST...SO LOOKS LIKE A DRIER DAY WITH
MAYBE JUST AN ISOLATED SHOWER IN MOUNTAINS.
ONLY MINIMAL CHANGES TO TEMPS THIS PACKAGE...STILL LOOKS LIKE A
GRADUAL WARMING TREND INTO MIDWEEK WITH NEAR NORMAL TEMPERATURES BY
WEDNESDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
USED A BLEND OF THE GFS AND ECMWF FOR WEDNESDAY THROUGH FRIDAY. THIS
LEAVES A WEAK HIGH PRESSURE SYSTEM OVER THE REGION...BUT POSSIBLY
ENOUGH MOISTURE TO FIRE SOME AFTERNOON SHOWERS/THUNDERSTORMS IN THE
MOUNTAINS. BY SATURDAY...SWITCHED TO A BLEND OF THE ECMWF AND GEFS
MEAN.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
WAS JUST A BIT FASTER WITH THE INCREASING MOISTURE MOVING UP THE
EASTERN SLOPES FOR THIS MORNING. AS A RESULT...NO THICK FOG SHOULD
BE SEEN AT DAWN.
THE 500 MB VORT MAX PASSES AROUND 15Z TO 16Z. BKW TO EKN CORRIDOR
SHOULD BE ALONG THE WESTERN EDGE OF THE MAIN SHOWER SHIELD
ASSOCIATED WITH THIS WAVE. THUNDER POSSIBLE NEAR THE VIRGINIA
BORDER. HAVE POPS PEAKING BY 14Z/15Z AROUND POCAHONTAS
COUNTY...BEFORE LOWERING AGAIN DURING THE 16Z TO 21Z PERIOD. HAVE
CEILINGS LOWERING AROUND 12Z ALONG THE EASTERN SLOPES INTO THE 2 TO
3 THSD FT BKN RANGE AND VSBY AROUND 5 MILES IN ANY RAIN SHOWERS.
FURTHER WEST HAVE MID DECK AROUND 10 THSD FT BEFORE SOME 4 TO 6 THSD
FT CEILINGS DEVELOPING BETWEEN 12Z TO 18Z.
ONCE THAT SUPPORT EXITS...DO NOT HAVE A GOOD HANDLE ON THE AMOUNT
AND HEIGHTS OF THE CLOUDS FOR LATE THIS AFTERNOON INTO THIS
EVENING...SAY 18Z TO 06Z. WILL LEAVE A SLIGHT CHANCE OF SHOWERS IN
FOR MANY AREAS...WITH WEAKER DISTURBANCES ALOFT...COMPARED TO THE
ONE THIS MORNING. VISIBILITY IN THE MOUNTAIN VALLEYS WILL LIKELY
DEPEND ON ANY RAIN TODAY...SO WILL HAVE TO BE FINE TUNED LATER
TODAY. THE MEDIUM CONFIDENCE MAINLY HAS TO DO WITH THESE
UNCERTAINTIES FOR LATE TODAY AND OVERNIGHT TONIGHT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: FOG MAY BE MORE WIDESPREAD 06Z TO 12Z MONDAY IF
THE RAIN TODAY AFFECTS A WIDER AREA.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY M H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY M H H H H H H H H H H H
AFTER 12Z MONDAY...
NO WIDESPREAD IFR CONDITIONS EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KTB/MZ
NEAR TERM...KTB
SHORT TERM...MZ
LONG TERM...RPY
AVIATION...KTB
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1005 AM EDT SUN AUG 19 2012
.SYNOPSIS...
A SEASONABLY STRONG UPPER LEVEL TROUGH OVER THE EASTERN HALF OF
THE U.S. WILL DOMINATE THE REGIONAL WEATHER PATTERN INTO THE
MIDDLE OF THE UPCOMING WEEK. SEVERAL WAVES OF LOW PRESSURE WILL
RIPPLE NORTHEASTWARD FROM THE GULF COAST ALONG A WAVY FRONTAL
BOUNDARY DRAPED ACROSS THE SOUTHEAST STATES AND SOUTHERN MID-
ATLANTIC. HIGH PRESSURE SHOULD RETURN TO THE AREA BY THE MIDDLE OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
CONVECTION DEVELOPING EARLY THIS MORNING AT NOSE OF HIGH THETA-E
RIDGE INTO WRN PA. THE SHOWERS SEEM TO HAVE SOME OROGRAPHIC
HELP/GENESIS...BUT ARE ALSO DISCONNECTED TO SFC SEEN IN STABLE
57/53F OB AT KAOO. WILL BUMP POPS A LITTLE AND WIDEN SCOPE A
LITTLE. LATEST RUC AND HRRR RUNS SPREAD THOSE SHRA/TSRA TO THE
NORTH AS THE MOISTURE ALOFT GETS BETTER AND UPGLIDE/ELEV INSTAB
COMBINES WITH HEATING/SFC INSTABILITY - ESP IN NWRN COS. SHIELD OF
GENERALLY LIGHT STRATIFORM RAIN WILL MOST LIKELY CONTINUE NE BUT
LIGHTEN UP AS DIURNAL CONVECTION DEVELOPS TO THE S - OVER VA/SRN
MD...ROBBING THE ERN COS OF BEST/DEEPEST MOISTURE. LAPSE RATES GET
STEEPER ALOFT THIS AFTN OVER THE WEST AS WELL AS THE 5H TROF MOVES
CLOSER. THE LOSS OF DAYTIME HEATING SHOULD SPELL AN AND TO THIS
ACTIVITY BY TNT...WITH PCPN FOCUS THEN SHIFTING TO SE PA.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 AM MONDAY/...
THE SECOND S/W CURRENTLY MOVG INTO THE SRN APPLCHNS WILL SPAWN A
WEAK SFC LOW OVER SC BY 21Z AND TRACK NEWD ACRS THE SRN MID-ATLC
STATES THRU THE END OF THE PD. THERE ARE SOME CONTINUING MDL DIFFS
WITH THE TRACK/PLACEMENT OF THE SFC LOW BY 12Z MON...WITH THE
UKMET THE SLOWEST SOLN AND NAM/ECMWF LOW POSITION NW OF THE
GFS/GEM. GIVEN THE UNCERTAINTY...A COMPROMISE OF EC/NAM/GFS/GEM IS
PREFERRED BY HPC AND PUTS THE LOW JUST E OF KWAL AT F36. BACKING
FLOW REGIME WILL TAP POOL OF HI PWAT OFF THE SE COAST AND SHOULD
WRAP OVRRNG PCPN N/NWWD FM THE DELMARVA BACK INTO SE PA ON NW SIDE
LOW TRACK LATE TNT INTO EARLY MON. HOWEVER DUE TO THE SPREAD IN
SOLNS WILL KEEP POPS MAINLY IN THE HIGH CHC RANGE OVR THE LWR SUSQ
VLY.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
FANTASTIC AGREEMENT AMONGST ALL FORECAST MODELS AND ENSEMBLE MEANS
OF THE MAJOR UPPER LEVEL FEATURES LEADS TO A HIGHER-THAN-NORMAL
CONFIDENCE FORECAST THROUGH THE MID RANGE AND FOR THE LONG TERM.
A HIGHLY ANOMALOUS UPPER TROUGH OVER THE CENTRAL AND SOUTHERN
STATES AT THE START OF THE PERIOD WILL FILL AND LIFT EASTWARD
DURING THE MID- WEEK. THUS...TEMPS SHOULD BE SLIGHTLY BELOW
NORMAL. PATTERN IS THEN MAINLY ZONAL. SFC FEATURES WILL DRIVE
MINOR FORECAST UNCERTAINTIES IN THE FIRST FEW DAYS...THOUGH. A
STALLED FRONT OVER THE SOUTHERN MID-ATLANTIC COULD BUCKLE A BIT
NORTHWARD AS A MOISTURE PLUME WITH A CONNECTION TO DEEP TROPICAL
MOISTURE OVER MEXICO IS DRAWN NORTHWARD ON THE EASTERN SIDE OF THE
UPPER TROUGH. A WAVE HAS BEEN FORECAST TO DEVELOP ALONG THE FRONT
FOR THE PAST FEW RUNS...AND SEE NO REASON TO DISCOUNT THAT WITH
SUCH A GOOD FEED ALOFT. THE CHANCES OF PRECIP ARE VERY MUCH IN
QUESTION...THOUGH. WILL HOLD WITH MUCH OF THE CURRENT
FORECAST...AND KEEP CHC RANGE POPS IN FOR MAINLY THE EAST SUN
NIGHT - MON NIGHT. AS BEFORE...HIGHEST POPS OF LIKELIES WILL BE
OVER THE SERN COS FOR MONDAY. NO THREAT FOR HEAVY RAIN WITH NO
REAL LOCAL FOCUS...NO PWAT ANOMALIES ACCORDING TO GEFS...AND THE
WAVE ALONG THE FRONT SHOULD BE MOBILE.
A SHORT WAVE STEMMING FROM THIS UPPER LEVEL LOW SHOULD MAKE ITS
WAY THROUGH TUESDAY AFTERNOON. DEPENDING ON TIMING...AND IF ITS
CONGRUENT WITH DIURNAL HEATING...THOUGH MAX TEMPS ARE SLIGHTLY
BELOW NORMAL...SHOULD ALLOW FOR SCT TSRA WITH COOL TEMPS ALOFT AS
THE TROUGH AXIS WILL BE OVERHEAD OR JUST APPROACHING. A STALLED
SFC LOW ON WEDNESDAY MAY BRING ENOUGH EASTERLY FLOW TO CAUSE
SHOWERS ALONG THE EASTERN PORTION OF THE CWA ON WEDNESDAY...THEN
MUCH OF THE WEEK LOOKS DRY AS A SFC ANTICYCLONE SETTLES IN FOR THE
LONG HAUL. D7/D8 WILL SEE THE RETURN OF VERY LOW POPS TO THE WEST
AS THE HIGH SLIDES TO THE EAST INTO THE WESTERN ATLANTIC.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
A BROAD UPPER LEVEL TROUGH EXTENDING SWD FROM JAMES BAY VORTEX
WILL PERSIST THROUGH EARLY NEXT WEEK. SEVERAL IMPULSES WILL
TRANSLATE AROUND THE BASE OF THE TROUGH THRU THE MS/TN/OH VLYS AND
INTERACT WITH A WAVY FRONTAL BOUNDARY STRETCHING FROM THE DEEP
SOUTH INTO THE SRN MID-ATLC STATES.
THERE IS STILL A LARGE SPREAD IN PCPN DETAILS...AND THIS TRANSLATES
INTO A LOW CONFIDENCE AVN FCST. IN GENERAL...WENT WITH A GRADUAL
LOWERING OF CLOUD BASES/VISBYS INTO MVFR RANGE TONIGHT. CONSENSUS
OF MDL DATA WOULD TEND TO FAVOR THE S-CENTRAL/SERN TERMINALS FOR
THE HIGHEST PROBABILITY FOR PCPN AND HAVE INSERTED VCSH. SOME IFR
CONDS ARE POSSIBLE TONIGHT BUT NOT CONFIDENT ENOUGH TO FCST IN THE
12Z TAFS.
OUTLOOK...
MON-TUE...VFR/MVFR WITH PERIODS OF LGT PCPN PSBL ESP SRN AIRFIELDS.
WED-THUR...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...DANGELO/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...DANGELO/FITZGERALD/CERU
AVIATION...DANGELO/STEINBUGL
AREA FORECAST DISCUSSION
NWS PADUCAH KY
320 PM CDT SUN AUG 19 2012
.UPDATE...
ISSUED AT 303 PM CDT SUN AUG 19 2012
SMALL CLUSTER OR TWO OF SHOWERS AND POSSIBLY A RUMBLE OR TWO OF
THUNDER HAVE DEVELOPED OUT OVER PORTIONS OF SE MO...ESP NORTH AND
WEST OF POPLAR BLUFF. THEREFORE...WILL UP POPS UP INTO THE SCT
RANGE FOR THE NEXT FEW HOURS.
UPDATE ISSUED AT 1104 AM CDT SUN AUG 19 2012
BASED UPON THE LATEST RADAR/STLT/NAM AND RUC PROGGED SOUNDINGS FOR
THE REST OF TODAY...AM INCLINED TO REDUCE SHOWER/STORM CHANCES
DOWN TO AROUND 10 PERCENT. EVEN THO WEAK IMPULSE ALOFT IS
APPROACHING IN CYCLONIC NW FLOW..THERE JUST SEEMS TO BE NO
INSTABILITY OR OVERALL MOISTURE TO WORK WITH /ESP BELOW 8000 FT/.
CANNOT RULE OUT AN ISOLD SHOWER OR SPRINKLE HERE AND THERE...BUT
CAPES PROGGED TO REMAIN LESS THAN 100 J/KG THIS AFTN...SO THUNDER
CHCS LOOK PRACTICALLY NIL.
ALSO...UPDATED THE AVIATION SECTION BELOW FOR THE UPCOMING 18Z
TAF FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 303 PM CDT SUN AUG 19 2012
BASED GENERALLY ON SAME REASONING AS IN THE UPDATE SECTION ABOVE...
AM INCLINED TO REDUCE SHOWER/STORM CHANCES DOWN TO AROUND 10
PERCENT FOR MONDAY/TUE ALSO. AGAIN...EVEN THO WEAK IMPULSES ALOFT
WILL CONTINUE TO ROTATE SSE WITHIN FAIRLY DEEP TROF /CYCLONIC FLOW/
OVER THE OHIO VALLEY...THERE JUST SEEMS TO BE VERY LITTLE
INSTABILITY AND OVERALL MOISTURE TO WORK WITH///ESP IN THE LOWEST
7000 TO 10000 FT. CANNOT RULE OUT AN ISOLD SHOWER OR SPRINKLES HERE
AND THERE...BUT CAPES PROGGED TO REMAIN LESS THAN 400 J/KG FOR THE
MOST PART THROUGH TUE...SO THUNDER CHCS CONTINUE TO LOOK PRACTICALLY
NIL.
AS FAR AS TEMPS ARE CONCERNED...WILL CONT TO IGNORE THE OBVIOUSLY
COLD MAV TEMP BIAS. EVEN THE MET MOS TEMPS SEEM TO BE RUNNING A
FEW DEGREES TOO COOL TODAY. HOWEVER...GIVEN THE FACT THAT THERE
MAY BE MORE IN THE WAY OF MID CLOUDS MONDAY...WILL STAY CLOSE TO
THE MET MOS NUMBERS TONIGHT THROUGH TUE NIGHT.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 303 PM CDT SUN AUG 19 2012
FOR WEDNESDAY THROUGH THURSDAY NIGHT...MODELS SHOW A BROAD UPPER
LEVEL RIDGE OVER THE REGION WITH HIGH PRESSURE AT THE SURFACE. THIS
WILL KEEP CONDITIONS DRY ACROSS THE PAH FORECAST AREA. SOUTHERLY
FLOW AND PLENTY OF SUNSHINE WILL KEEP TEMPERATURES NEAR NORMAL WITH
HIGHS IN THE UPPER 80S AND LOWS IN THE LOWER TO MIDDLE 60S.
MODELS DIVERGE ON FRIDAY. THE 00Z ECMWF SHOWED AN UPPER LEVEL LOW
SLIDING INTO THE AREA...BRINGING SOME QPF TO MAINLY SOUTHERN
PORTIONS OF THE PAH FORECAST AREA. THE 12Z ECMWF IS MUCH LESS
PRONOUNCED WITH THIS FEATURE AND KEEPS ANY PRECIP JUST WEST OF OUR
AREA. THE LATEST GFS...ON THE OTHER HAND...BRINGS A SURFACE LOW OUT
OF THE PLAINS AND BRINGS CHANCES OF PRECIP INTO OUR WESTERN COUNTIES
FRIDAY NIGHT AND THE ENTIRE PAH FA ON SATURDAY. MODELS LACK ANY
REAL CONSISTENCY...SO JUST STUCK WITH SLIGHT TO VERY LOW CHANCE
POPS FOR NOW...WITH SLIGHTLY HIGHER POPS ACROSS OUR SOUTHERN
COUNTIES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 303 PM CDT SUN AUG 19 2012
BASED UPON THE LATEST RADAR/STLT/NAM AND RUC PROGGED SOUNDINGS FOR
THE REST OF TODAY THROUGH EARLY AFTN MON...AM INCLINED TO REDUCE
SHOWER/STORM CHANCES DOWN TO AROUND 10 PERCENT. EVEN THO WEAK
IMPULSE ALOFT IS APPROACHING IN CYCLONIC NW FLOW ALOFT...THERE
JUST SEEMS TO BE NO INSTABILITY OR OVERALL MOISTURE TO WORK
WITH...ESP BELOW 8000 FT. CANNOT RULE OUT AN ISOLD SHOWER OR
SPRINKLE HERE AND THERE...BUT CAPES PROGGED TO REMAIN LESS THAN
100 J/KG THIS AFTN...SO THUNDER CHCS LOOK PRACTICALLY NIL NEAR TAF
SITES. WILL GO WITH ONLY VFR MID CLOUDS FROM TIME TO TIME. WINDS
WILL LIGHT IN DAYTIME...CALM AT NIGHT.
&&
.FIRE WEATHER...
ISSUED AT 303 PM CDT SUN AUG 19 2012
VERY DRY AIR WILL REMAIN IN PLACE FOR THE FIRST HALF OF THE
UPCOMING WEEKS. IN FACT...SOME LOCATIONS MAY SEE RELATIVE
HUMIDITIES DIP TO NEAR 20 PERCENT BY TUESDAY. IN ADDITION...10
HOUR FUEL MOISTURES HAVE NOW FALLEN BACK INTO THE 6 TO 10 PERCENT
RANGE. THUS...THE RISK OF RAPID WILDFIRE GROWTH WILL BE ELEVATED
DURING THIS TIME FRAME. WINDS...BOTH AT THE SURFACE AND ALOFT...
SHOULD REMAIN GENERALLY LIGHT.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...MEFFERT
SHORT TERM...MEFFERT
LONG TERM....RST
AVIATION...MEFFERT
FIRE WEATHER...MEFFERT
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1143 AM CDT SUN AUG 19 2012
.UPDATE...
ISSUED AT 1104 AM CDT SUN AUG 19 2012
BASED UPON THE LATEST RADAR/STLT/NAM AND RUC PROGGED SOUNDINGS FOR
THE REST OF TODAY...AM INCLINED TO REDUCE SHOWER/STORM CHANCES
DOWN TO AROUND 10 PERCENT. EVEN THO WEAK IMPULSE ALOFT IS
APPROACHING IN CYCLONIC NW FLOW..THERE JUST SEEMS TO BE NO
INSTABILITY OR OVERALL MOISTURE TO WORK WITH /ESP BELOW 8000 FT/.
CANNOT RULE OUT AN ISOLD SHOWER OR SPRINKLE HERE AND THERE...BUT
CAPES PROGGED TO REMAIN LESS THAN 100 J/KG THIS AFTN...SO THUNDER
CHCS LOOK PRACTICALLY NIL.
ALSO...UPDATED THE AVIATION SECTION BELOW FOR THE UPCOMING 18Z
TAF FORECAST.
&&
.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 1104 AM CDT SUN AUG 19 2012
BASED GENERALLY ON SAME REASONING AS IN THE UPDATE SECTION ABOVE...
AM INCLINED TO REDUCE SHOWER/STORM CHANCES DOWN TO AROUND 10
PERCENT FOR MONDAY/TUE ALSO. AGAIN...EVEN THO WEAK IMPULSES ALOFT
WILL CONTINUE TO ROTATE SSE WITHIN FAIRLY DEEP TROF /CYCLONIC FLOW/
OVER THE OHIO VALLEY...THERE JUST SEEMS TO BE VERY LITTLE
INSTABILITY AND OVERALL MOISTURE TO WORK WITH///ESP IN THE LOWEST
7000 TO 10000 FT. CANNOT RULE OUT AN ISOLD SHOWER OR SPRINKLES HERE
AND THERE...BUT CAPES PROGGED TO REMAIN LESS THAN 400 J/KG FOR THE
MOST PART THROUGH TUE...SO THUNDER CHCS CONTINUE TO LOOK PRACTICALLY
NIL.
AS FAR AS TEMPS ARE CONCERNED...WILL CONT TO IGNORE THE OBVIOUSLY
COLD MAV TEMP BIAS. EVEN THE MET MOS TEMPS SEEM TO BE RUNNING A
FEW DEGREES TOO COOL TODAY. HOWEVER...GIVEN THE FACT THAT THERE
MAY BE MORE IN THE WAY OF MID CLOUDS MONDAY...WILL STAY CLOSE TO
THE MET MOS NUMBERS TONIGHT THROUGH TUE NIGHT.
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 142 AM CDT SUN AUG 19 2012
THERE CONTINUES TO BE A GOOD DEAL OF INCONSISTENCY BETWEEN THE
MODELS IN THE EXTENDED WITH REGARDS TO HOW THEY HANDLE THE UPPER
LEVEL PATTERN. BY 12Z WEDNESDAY...THE 00Z GFS SHOWS A DEPARTING
TROUGH WITH A UPPER RIDGE DEVELOPING OVER THE NEXT FEW DAYS. THE
ECWMF CONTINUES TO ADVERTISE A CLOSED LOW DEVELOPING OVER ARKANSAS
WHICH MOVES EAST ON WEDNESDAY TOWARD NORTHERN MS/AL...AND RIDGING
ALOFT TRIES TO TAKE PLACE ON THURSDAY.
WHILE THE MATTER OF PRECIPITATION IS MOOT BECAUSE OF THE LACK OF
MOISTURE...THE MAIN CHALLENGES FOR WED-FRI WILL BE
TEMPERATURES/WIND. THE GFS AND THE GFS ENSEMBLE MEAN INDICATES HIGH
PRESSURE AT THE SFC ON WEDNESDAY WHICH MOVES EAST ON WEDNESDAY NIGHT
AND THURSDAY...AND THAT IS WHEN OUR WARM UP BEGINS. THE ECMWF SHOWS
THE SFC HIGH ALREADY TO OUR EAST ON WEDNESDAY AND AS SUCH...HAS
THINGS HEATING UP QUICKER DUE TO A QUICKER SHIFT TO WEAK SOUTHERLY
FLOW. WILL STICK WITH MID 80S FOR WEDNESDAY AND CONTINUE TO SHOW THE
INCREASE IN THE HEAT THROUGH THE END OF THE WEEK.
THE GFS AND ECMWF ARE IN FAIRLY GOOD AGREEMENT WITH BRINGING AN
UPPER LEVEL TROUGH TOWARD THE AREA ON FRIDAY...AND BRINGING
PRECIPITATION INTO THE AREA BY FRIDAY NIGHT WHICH LINGERS INTO
SATURDAY. NOT SURE HOW THE TIMING AND ACTUAL COVERAGE OF
PRECIPITATION WILL WORK OUT AT THIS POINT...BUT THE END OF THE WEEK
AND INTO THE WEEKEND LOOKS UNSETTLED AT THIS POINT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1104 AM CDT SUN AUG 19 2012
BASED UPON THE LATEST RADAR/STLT/NAM AND RUC PROGGED SOUNDINGS FOR
THE REST OF TODAY THROUGH EARLY AFTN MON...AM INCLINED TO REDUCE
SHOWER/STORM CHANCES DOWN TO AROUND 10 PERCENT. EVEN THO WEAK
IMPULSE ALOFT IS APPROACHING IN CYCLONIC NW FLOW ALOFT...THERE
JUST SEEMS TO BE NO INSTABILITY OR OVERALL MOISTURE TO WORK
WITH...ESP BELOW 8000 FT. CANNOT RULE OUT AN ISOLD SHOWER OR
SPRINKLE HERE AND THERE...BUT CAPES PROGGED TO REMAIN LESS THAN
100 J/KG THIS AFTN...SO THUNDER CHCS LOOK PRACTICALLY NIL. WILL GO
WITH ONLY VFR MID CLOUDS FROM TIME TO TIME. WINDS WILL VERY LIGHT
NRLY IN DAYTIME...CALM AT NIGHT.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...MEFFERT
SHORT TERM...MEFFERT
AVIATION...MEFFERT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1244 PM EDT SUN AUG 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE STATE TODAY WHILE A COLD FRONT
BECOMES NEARLY STATIONARY OVER THE GULF OF MAINE. THE NEXT LOW
PRESSURE SYSTEM WILL MOVE ACROSS THE REGION MONDAY NIGHT INTO
TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
1245 PM UPDATE...HIGH PRESSURE WILL LINGER OVER THE REGION TODAY,
KEEPING LOTS OF SUNSHINE AROUND MUCH OF THE AREA. THE EXCEPTION
WILL BE COASTAL WASHINGTON COUNTY, WHERE CLOUDS ASSOCIATED WITH A
COLD FRONT JUST OFF THE COAST WILL REMAIN THROUGH MUCH OF THE DAY.
THE PREVIOUS FORECAST HAS THIS COVERED, SO ONLY MINOR ADJUSTMENTS
WERE MADE.
PREVIOUS DISCUSSION...A FRONTAL SYSTEM OFF THE DOWNEAST COAST
WILL DRIFT SLOWLY TO THE EAST OVER THE NEXT 24 HOURS AS WEAK HIGH
PRESSURE BUILDS IN FROM THE WEST. PRIMARY TASK IS TIMING OF EXIT
OF PRECIPITATION FROM DOWNEAST COAST. FOR POP GRIDS UNTIL 1200Z
WILL INITIALIZE WITH RUC13 WITH SOME MANUAL ADJUSTMENT THEN
TRANSITION TO A BLEND OF THE NAM12...GFS40...SREF AND ECMWF TO
INITIALIZE POP GRIDS. HAVE USED A BLEND OF THE NAM12 AND GMOS FOR
WINDS GRIDS. GMOS WAS USED FOR TEMPERATURE AND DEW POINT AND WILL
DECREASE MINIMUM TEMPERATURE TONIGHT WITH SEASONABLY COOL AIR MASS
IN PLACE. QPF GRIDS GENERATED WITH A BLEND OF THE
NAM80...SREF....GFS AND ECMWF.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
THE MAIN FOCUS WILL BE ON TUESDAY IN REGARDS TO AN APPROACHING
COLD FRONT FROM THE WEST AND LOW PRES MOVING ACROSS THE SOUTHERN
GULF OF MAINE.
MONDAY LOOKS TO BE A DRY AND PLEASANT DAY FOR THE MOST PART W/THE
EXCEPTION FOR A WEAK DISTURBANCE MOVING ACROSS THE REGION IN THE
AFTERNOON. THIS FEATURE COULD DELIVER A QUICK SHOWER TO THE WEST
AND NORTHWEST AREAS. ALL THE SHORT RANGE GUIDANCE INCLUDING THE
00Z ECMWF SHOWS SOME FORCING IN THE MID AND UPPER LEVELS BUT THE
BIGGEST INGREDIENT LACKING IS THE DEEP MOISTURE. THEREFORE, STAYED
W/20-30% POPS IN THE AFOREMENTIONED AREAS. ACCEPTED THE DAYCREW`S
MAXES OF UPPER 70S TO AROUND 80.
ANOTHER S/WV IN CONJUNCTION W/A WEAK COLD FRONT IS SHOWN BY THE
ECMWF/GFS AND CANADIAN GLOBAL TO MOVE ACROSS THE REGION BY TUESDAY
AFTERNOON. THE LATEST RUNS INCLUDING THE NAM HAVE BACKED OFF ON
PRECIP CHANCES AND AVAILABLE MOISTURE KEEPING THE PASSAGE DRY FOR
THE MOST PART. THE NAM IS THE MOST AGGRESSIVE W/THE MOISTURE AND
INSTABILITY WHILE THE GFS SHOWS MORE STABILITY. ATTM, THE DECISION
WAS TO KEEP IN LINE W/THE DAYCREW`S THINKING AND CONTINUE W/30-40%
POPS MAINLY ACROSS THE NORTH AND CENTRAL AREAS. TSTMS WERE ADDED
FOR TUESDAY AFTERNOON TAKING A BLEND OF THE NAM AND GFS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE WEAK COLD FRONT WILL SLIDE TO THE EAST TUESDAY NIGHT FOLLOWED
BY HIGH PRES FOR WEDNESDAY KEEPING CONDITIONS ON THE DRY AND
PLEASANT SIDE. HUNG ONTO THE DAYCREW`S MAX TEMPERATURES FOR
WEDNESDAY W/READINGS MAXING OUT IN THE LOW TO MID 70S.
THE 00Z RUN OF THE ECMWF AND GFS SHOW ANOTHER FRONTAL BOUNDARY
MOVING INTO THE CWA ON THURSDAY. SOME MID LEVEL FORCING IN THERE
BUT ONCE AGAIN DEEP MOISTURE IS LIMITED. THEREFORE, DECIDED ON
20-30% FOR THURSDAY AFTERNOON W/THE HIGHEST PERCENTAGES ACROSS THE
NORTHERN PART OF THE CWA. ATTM, KEPT THE MENTION OF THUNDER OUT OF
THE FCST AND WENT W/JUST SHOWERS. THE GFS QUICKLY MOVES THIS
FRONTAL BOUNDARY OFF TO THE EAST AND DRIES THINGS OUT FOR FRIDAY
WHILE THE LATEST RUN OF THE ECMWF KEEPS THE FRONT BACK LONGER AND
HAS ANOTHER AREA OF PRECIP SHOWING UP BY EARLY FRIDAY. THIS IS A
DIFFERENT SCENARIO THAN THE 12Z RUN WHICH WAS CLOSER TO THE 00Z
RUN OF THE GFS. THE 00Z RUN OF THE CANADIAN GLOBAL IS IN LINE
W/THE ECWMF. LOOKING AT THE SYNOPTIC PATTERN OF THE LONG WAVE TROF
HANGING ON ACROSS THE NE AND NO SIGNIFICANT MOISTURE AVAILABLE,
THINKING HERE IS THAT THE ECMWF AND CANADIAN COULD BE OVERDONE
W/THEIR QPF. THE DECISION WAS TO GO W/A DRY FCST FOR FRIDAY W/MAX
TEMPERATURES OF LOW TO MID 70S.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
NEAR TERM: VFR CONDITIONS EXPECTED NEXT 24 HOURS. SOME IFR/MVFR
KBHB EARLY THIS MORNING DUE TO CEILING.
SHORT TERM: SHOULD BE VFR PRETTY MUCH THROUGH THE PERIOD. A BRIEF
PERIOD OF MVFR CONDITIONS COULD BE SEEN ON TUESDAY W/THE PASSAGE
OF THE COLD FRONT.
&&
.MARINE...
NEAR TERM: HAVE USED A 50/50 BLEND OF THE NAM12 AND GFS40 TO
INITIALIZE GRIDS THEN LOWER WIND SPEED BY 20 PERCENT. FOR WAVES:
HAVE USE THE NAM/SWAN TO POPULATE GRIDS. PRIMARY SOURCE OF WAVES
IS 1 TO 2 FOOT LONGER PERIOD SWELL. BASED ON WNA SPECTRAL THIS
WAVE GROUP FROM SOUTHEAST AT 9 TO 11 SECONDS.
SHORT TERM: NO HEADLINES ANTICIPATED. THE MAIN FOCUS WILL BE THE
SE SWELL DEVELOPING AND HANGING ON THROUGH THE PERIOD. SUSTAINED
WINDS OF 10 KTS AND A SEA/SWELL STATE OF 2-3 FT W/A PERIOD OF 8-9
SECONDS.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HASTINGS/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...HASTINGS/MIGNONE
MARINE...HASTINGS/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
322 PM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF WEAK UPPER LEVEL LOW PRESSURE DISTURBANCES WILL CROSS
THE UPPER OHIO VALLEY EARLY THIS WEEK AND GENERATE A FEW SHOWERS
AND POSSIBLY THUNDERSTORMS. HIGH PRESSURE WILL MOVE INTO THE AREA
ON WEDNESDAY, RETURNING DRY WEATHER FOR THE MID-WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
EXTENDING FROM THE JAMES BAY IN CANADA ACROSS THE GREAT LAKES AND
INTO ILLINOIS. THIS LEAVES THE OHIO UPPER VALLEY IN A
SOUTHWESTERLY FLOW ON THE EASTERN SIDE OF THE BROAD BASE OF THE
TROUGH. SHOWERS HAVE COME TO AN END ACROSS THE SOUTHEAST RIDGES AS
THE INITIAL SHORT WAVE HAS MOVED OUT OF THE AREA. VORT ENERGY
ACROSS NORTHERN OHIO IS NOW BEGINNING TO INITIATE CONVECTION
THERE. THE LATEST LAPS ANALYSIS INDICATES WEAK CAPE BTW 300-800
J/KG AND SPC RAP MESOSCALE ANALYSIS INDICATES WEAK BULK EFFECTIVE
SHEAR AT 25KTS ACROSS THE FORECAST AREA.
THROUGH THE EARLY EVENING...THE RAP INDICATES THAT THE FOCUS OF
FORCING WITH VORT ENERGY WILL PASS NORTHWEST OF THE CWA. STILL, DAYTIME
HEATING WITH AROUND 1000 J/KG CAPE AND STEEPENING LOW- LEVEL AND
MID-LEVEL LAPSE RATES MAY BE ENOUGH FOR SCATTERED SHOWERS TO
DEVELOP. FORECAST ALSO CONSISTS OF ISOLATED THUNDERSTORMS, GIVEN
THE LACK OF FORCING AND WEAK INSTABILITY ANTICIPATED. WITH THE
LACK OF COVERAGE OF CONVECTION THIS AFTERNOON INTO THE EARLY
EVENING, ANTICIPATE ANY SHOWERS OR STORMS TO BE BRIEF AS THEY MOVE
ACROSS THE AREA. HIGH TEMPS THIS AFTERNOON ARE A BLEND OF THE LAPS
AND RECENT OBS TRENDS, WITH HIGHS RANGING FROM THE LOWER 70S
ACROSS THE EASTERN RIDGES TO THE LOWER 80S IN PORTIONS OF EASTERN
OHIO AND NORTHERN WV.
TONIGHT...WRF-NMM/HRRR HIRES MODELS SUPPORT CONVECTION DIMINISHING
FAIRLY QUICKLY AFTER 00Z. HAVE MAINTAINED SCHC POPS EARLY
OVERNIGHT AS ANY LINGERING CONVECTION SLIDES EAST OF THE AREA.
THERE IS LOW CONFIDENCE IN PATCHY FOG DEVELOPING IN THE RIVER
VALLEYS DURING THE PRE-DAWN HOURS AS THIS WILL BE DEPENDENT ON HOW
MUCH RAINFALL LOCALITIES RECEIVE TODAY. THUS, HAVE LEFT FOG OUT OF
THE PUBLIC FORECAST AT THIS TIME. OVERNIGHT TEMPS ARE CLOSER TO
THE COOLER MAV GUIDANCE WITH LOWS RANGING FROM THE LOW TO MID 50S
ACROSS MUCH OF THE AREA.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THERE IS ECMWF/GFS/NAM AGREEMENT THAT THE BROAD MID-LEVEL TROUGH
WILL REMAIN ACROSS THE OHIO VALLEY ON MONDAY AND AMPLIFY AS ITS
AXIS SWINGS INTO THE UPPER OHIO VALLEY LATE TUESDAY INTO
WEDNESDAY. WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW
AHEAD OF THIS FEATURE AND THE MAJORITY OF MODEL SOLUTIONS SHOWING
WEAK INSTABILITY EACH DAY, CHC POPS WITH SCHC THUNDER IS FORECAST
FOR MONDAY WITH SCHC POPS/THUNDER ON TUESDAY. TEMPS WILL BE AROUND
5 DEGREES BELOW NORMAL THROUGH THIS PERIOD.
A MODEL CONSENSUS INDICATES THE TROUGH SLIDING EAST OF AREA AND
HIGH PRESSURE BUILDING IN FROM THE WEST ON WEDNESDAY. THIS WILL
ALLOW FOR A DRY FORECAST WITH MORE ABUNDANT SUNSHINE ON WEDNESDAY.
WITH INCREASED SUNSHINE TEMPS WILL WARM CLOSER TO SEASONAL NORMALS
ACROSS THE AREA.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
CONSENSUS OF RECENT ECMWF AND NAEFS MODEL OUTPUT CONTINUES TO SHOW
BROAD HIGH PRESSURE UNDER WEAK FLOW ALOFT ACROSS THE EASTERN U.S.
INTO THE WEEKEND. HENCE, WILL MAINTAIN A FORECAST OF DRY AND
RELATIVELY CLOUDFREE CONDITIONS THROUGH THE PERIOD.
THIS SHOULD TRANSLATE TO EACH DAY HAVING A LARGER THAN NORMAL
DIURNAL TEMPERATURE RANGE. CONCUR WITH HPC THINKING, WITH SUPPORT
FROM GFS AND ECMWF MOS AND NAEFS MEDIAN VALUES, THAT LOWS THURSDAY
AND FRIDAY CAN BE UP TO 5 DEGREES COOLER THAN NORMAL, WHILE HIGHS BE
NEAR NORMAL. WITH POTENTIAL OF SURFACE DEW POINTS CLIMBING TO NEAR
NORMAL VALUES THIS WEEKEND, EXPECT WEEKEND LOWS TO LIKEWISE BE NEAR
NORMAL, WHILE HIGHS BE UP TO 5 DEGREES WARMER THAN NORMAL.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
EXPECT MAINLY VFR ACROSS THE UPPER OHIO VALLEY THROUGH 07Z.
PER BLEND OF RECENT RADAR DATA AND HRRR MODEL OUTPUT FORESEE ONLY
POTENTIAL OF RESTRICTIONS WOULD BE WITH ISOLATED SHOWERS AND
THUNDERSTORMS LATE THIS AFTERNOON.
RECENT GFS LAMP AND NAM MOS CONTINUE TO SUPPORT THE IDEA OF AN IFR
RIVER VALLEY FOG EPISODE 07Z-13Z, THAT MAY AFFECT NEARBY TAF SITES.
HOWEVER, AT THIS JUNCTURE HAD ONLY ENOUGH CONFIDENCE TO INCLUDE MVFR
VISIBILITIES FOR MOST TAF SITES. DID MENTION IFR VISIBILITIES AT
KMGW, KHLG, AND KLBE, WHERE SURFACE DEW POINTS THIS AFTERNOON HAVE
CLIMBED INTO THE UPPER 50S, AN INDICATION THAT LATE NIGHT LOW
TEMPERATURES COULD BE COLDER THAN UPS FOG TECHNIQUE CROSSOVER
VALUES.
THE OTHER KEY TO FOG DEVELOPMENT LATE TONIGHT WOULD BE THE
LOCATION AND EXTENT OF SHOWERS LATE THIS AFTERNOON, AND THEIR
SUBSEQUENT EFFECT ON MOISTENING A SHALLOW TEMPERATURE-INVERSION
CAPPED SURFACE LAYER TONIGHT.
EXPECT THE REST OF MONDAY TO BE MAINLY VFR, ALTHOUGH AGAIN CANNOT
COMPLETELY RULE OUT THE POTENTIAL OF A BRIEF RESTRICTION WITH
ISOLATED AFTERNOON THUNDERSTORMS.
.OUTLOOK/ MONDAY NIGHT THROUGH FRIDAY/...
GENERALLY VFR. RESTRICTIONS MAY ACCOMPANY SCATTERED THUNDERSTORMS
MONDAY EVENING, AND PATCHY RIVER VALLEY FOG EACH MORNING.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
216 PM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF WEAK UPPER LEVEL LOW PRESSURE DISTURBANCES WILL CROSS
THE UPPER OHIO VALLEY EARLY THIS WEEK AND GENERATE A FEW SHOWERS
AND POSSIBLY THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO CHANGE
WX GRIDS WORDING TO COVERAGE WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS POSSIBLE THIS AFTERNOON.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
EXTENDING FROM THE JAMES BAY IN CANADA ACROSS THE GREAT LAKES AND
INTO ILLINOIS. THIS LEAVES THE OHIO UPPER VALLEY IN A SOUTHWESTERLY
FLOW ON THE EASTERN SIDE OF THE BROAD BASE OF THE TROUGH. SHOWERS
HAVE COME TO AN END ACROSS THE SOUTHEAST RIDGES AS THE INITIAL
SHORT WAVE HAS MOVED OUT OF THE AREA. VORT ENERGY ACROSS NORTHERN
OHIO IS NOW BEGINNING TO INITIATE CONVECTION THERE. THE LATEST
LAPS ANALYSIS INDICATES WEAK CAPE BTW 300-800 J/KG AND SPC RAP
MESOSCALE ANALYSIS INDICATES WEAK BULK EFFECTIVE SHEAR AT 25KTS
ACROSS THE FORECAST AREA.
THIS AFTERNOON INTO THE EARLY EVENING...ALTHOUGH THE RAP INDICATES
THAT THE FOCUS OF FORCING WITH VORT ENERGY WILL PASS NORTHWEST OF
THE CWA, DAYTIME HEATING WITH AROUND 1000 J/KG CAPE AND STEEPENING
LOW-LEVEL AND MID-LEVEL LAPSE RATES SHOULD BE ENOUGH FOR
SCATTERED SHOWERS TO DEVELOP. FORECAST ALSO CONSISTS OF ISOLATED
THUNDERSTORMS, GIVEN THE LACK OF FORCING AND WEAK INSTABILITY
ANTICIPATED. WITH THE LACK OF COVERAGE OF CONVECTION THIS
AFTERNOON INTO THE EARLY EVENING, ANTICIPATE ANY SHOWERS OR STORMS
TO BE BRIEF AS THEY MOVE ACROSS THE AREA. HIGH TEMPS THIS
AFTERNOON ARE A BLEND OF THE LAPS AND RECENT OBS TRENDS, WITH
HIGHS RANGING FROM THE LOWER 70S ACROSS THE EASTERN RIDGES TO THE
LOWER 80S IN PORTIONS OF EASTERN OHIO AND NORTHERN WV.
TONIGHT...WRF-NMM/HRRR HIRES MODELS SUPPORT CONVECTION DIMINISHING
FAIRLY QUICKLY AFTER 00Z. HAVE MAINTAINED SCHC POPS EARLY
OVERNIGHT AS LINGERING CONVECTION SLIDES EAST OF THE AREA. THERE
IS LOW CONFIDENCE IN PATCHY FOG DEVELOPING IN THE RIVER VALLEYS
DURING THE PRE-DAWN HOURS AS THIS WILL BE DEPENDENT ON HOW MUCH
RAINFALL LOCALITIES RECEIVE TODAY. THUS, HAVE LEFT FOG OUT OF THE
FORECAST AT THIS TIME. OVERNIGHT TEMPS ARE CLOSER TO THE COOLER
MAV GUIDANCE WITH LOWS RANGING FROM THE LOW TO MID 50S ACROSS MUCH
OF THE AREA.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
THE MID-LEVEL TROUGH AXIS OF THE AFOREMENTIONED SYSTEM IS PROGGED
TO LINGER WEST 0F...OR OVER THE UPPER OHIO AREA THROUGH MID WEEK.
HOWEVER...GRADUAL DRYING AND STRENGTHENING OF SURFACE HIGH
PRESSURE NORTH OF THE OHIO WL FURTHER LIMIT PRECIP CHANCES AND
SLIGHT POPS WERE SHIFTED EASTWARD ON TUESDAY AND TAPERED OFF BY
WEDNESDAY.
TEMPS UNDER THE MID/UPR TROUGH WERE FORECAST USING A GUIDANCE
BLEND AND WL REMAIN APPROXIMATELY 5 DEGREES BELOW NORMAL THROUGH
THE SHORT TERM PERIOD.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
CONSENSUS OF RECENT ECMWF AND NAEFS MODEL OUTPUT CONTINUES TO SHOW
BROAD HIGH PRESSURE UNDER WEAK FLOW ALOFT ACROSS THE EASTERN U.S.
INTO THE WEEKEND. HENCE, WILL MAINTAIN A FORECAST OF DRY AND
RELATIVELY CLOUD FREE CONDITIONS THROUGH THE PERIOD.
THIS SHOULD TRANSLATE TO EACH DAY HAVING A LARGER THAN NORMAL
DIURNAL TEMPERATURE RANGE. CONCUR WITH HPC THINKING, WITH SUPPORT
FROM GFS AND ECMWF MOS AND NAEFS MEDIAN VALUES, THAT LOWS THURSDAY
AND FRIDAY CAN BE UP TO 5 DEGREES COOLER THAN NORMAL, WHILE HIGHS BE
NEAR NORMAL. WITH POTENTIAL OF SURFACE DEW POINTS CLIMBING TO NEAR
NORMAL VALUES THIS WEEKEND, EXPECT WEEKEND LOWS TO LIKEWISE BE NEAR
NORMAL, WHILE HIGHS BE UP TO 5 DEGREES WARMER THAN NORMAL.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
EXPECT MAINLY VFR ACROSS THE UPPER OHIO VALLEY THROUGH 07Z.
PER BLEND OF RECENT RADAR DATA AND HRRR MODEL OUTPUT FORESEE ONLY
POTENTIAL OF RESTRICTIONS WOULD BE WITH ISOLATED SHOWERS AND
THUNDERSTORMS LATE THIS AFTERNOON.
RECENT GFS LAMP AND NAM MOS CONTINUE TO SUPPORT THE IDEA OF AN IFR
RIVER VALLEY FOG EPISODE 07Z-13Z, THAT MAY AFFECT NEARBY TAF SITES.
HOWEVER, AT THIS JUNCTURE HAD ONLY ENOUGH CONFIDENCE TO INCLUDE MVFR
VISIBILITIES FOR MOST TAF SITES. DID MENTION IFR VISIBILITIES AT
KMGW, KHLG, AND KLBE, WHERE SURFACE DEW POINTS THIS AFTERNOON HAVE
CLIMBED INTO THE UPPER 50S, AN INDICATION THAT LATE NIGHT LOW
TEMPERATURES COULD BE COLDER THAN UPS FOG TECHNIQUE CROSSOVER
VALUES.
THE OTHER KEY TO FOG DEVELOPMENT LATE TONIGHT WOULD BE THE
LOCATION AND EXTENT OF SHOWERS LATE THIS AFTERNOON, AND THEIR
SUBSEQUENT EFFECT ON MOISTENING A SHALLOW TEMPERATURE-INVERSION
CAPPED SURFACE LAYER TONIGHT.
EXPECT THE REST OF MONDAY TO BE MAINLY VFR, ALTHOUGH AGAIN CANNOT
COMPLETELY RULE OUT THE POTENTIAL OF A BRIEF RESTRICTION WITH
ISOLATED AFTERNOON THUNDERSTORMS.
.OUTLOOK/ MONDAY NIGHT THROUGH FRIDAY/...
GENERALLY VFR. RESTRICTIONS MAY ACCOMPANY SCATTERED THUNDERSTORMS
MONDAY EVENING, AND PATCHY RIVER VALLEY FOG EACH MORNING.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
150 PM EDT SUN AUG 19 2012
.SYNOPSIS...
A SERIES OF WEAK UPPER LEVEL LOW PRESSURE DISTURBANCES WILL CROSS
THE UPPER OHIO VALLEY EARLY THIS WEEK AND GENERATE A FEW SHOWERS
AND POSSIBLY THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO CHANGE
WX GRIDS WORDING TO COVERAGE WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS POSSIBLE THIS AFTERNOON.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
EXTENDING FROM THE JAMES BAY IN CANADA ACROSS THE GREAT LAKES AND
INTO ILLINOIS. THIS LEAVES THE OHIO UPPER VALLEY IN A SOUTHWESTERLY
FLOW ON THE EASTERN SIDE OF THE BROAD BASE OF THE TROUGH. SHOWERS
HAVE COME TO AN END ACROSS THE SOUTHEAST RIDGES AS THE INITIAL
SHORT WAVE HAS MOVED OUT OF THE AREA. VORT ENERGY ACROSS NORTHERN
OHIO IS NOW BEGINNING TO INITIATE CONVECTION THERE. THE LATEST
LAPS ANALYSIS INDICATES WEAK CAPE BTW 300-800 J/KG AND SPC RAP
MESOSCALE ANALYSIS INDICATES WEAK BULK EFFECTIVE SHEAR AT 25KTS
ACROSS THE FORECAST AREA.
THIS AFTERNOON INTO THE EARLY EVENING...ALTHOUGH THE RAP INDICATES
THAT THE FOCUS OF FORCING WITH VORT ENERGY WILL PASS NORTHWEST OF
THE CWA, DAYTIME HEATING WITH AROUND 1000 J/KG CAPE AND STEEPENING
LOW-LEVEL AND MID-LEVEL LAPSE RATES SHOULD BE ENOUGH FOR
SCATTERED SHOWERS TO DEVELOP. FORECAST ALSO CONSISTS OF ISOLATED
THUNDERSTORMS, GIVEN THE LACK OF FORCING AND WEAK INSTABILITY
ANTICIPATED. WITH THE LACK OF COVERAGE OF CONVECTION THIS
AFTERNOON INTO THE EARLY EVENING, ANTICIPATE ANY SHOWERS OR STORMS
TO BE BRIEF AS THEY MOVE ACROSS THE AREA. HIGH TEMPS THIS
AFTERNOON ARE A BLEND OF THE LAPS AND RECENT OBS TRENDS, WITH
HIGHS RANGING FROM THE LOWER 70S ACROSS THE EASTERN RIDGES TO THE
LOWER 80S IN PORTIONS OF EASTERN OHIO AND NORTHERN WV.
TONIGHT...WRF-NMM/HRRR HIRES MODELS SUPPORT CONVECTION DIMINISHING
FAIRLY QUICKLY AFTER 00Z. HAVE MAINTAINED SCHC POPS EARLY
OVERNIGHT AS LINGERING CONVECTION SLIDES EAST OF THE AREA. THERE
IS LOW CONFIDENCE IN PATCHY FOG DEVELOPING IN THE RIVER VALLEYS
DURING THE PRE-DAWN HOURS AS THIS WILL BE DEPENDENT ON HOW MUCH
RAINFALL LOCALITIES RECEIVE TODAY. THUS, HAVE LEFT FOG OUT OF THE
FORECAST AT THIS TIME. OVERNIGHT TEMPS ARE CLOSER TO THE COOLER
MAV GUIDANCE WITH LOWS RANGING FROM THE LOW TO MID 50S ACROSS MUCH
OF THE AREA.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
THE MID-LEVEL TROUGH AXIS OF THE AFOREMENTIONED SYSTEM IS PROGGED
TO LINGER WEST 0F...OR OVER THE UPPER OHIO AREA THROUGH MID WEEK.
HOWEVER...GRADUAL DRYING AND STRENGTHENING OF SURFACE HIGH
PRESSURE NORTH OF THE OHIO WL FURTHER LIMIT PRECIP CHANCES AND
SLIGHT POPS WERE SHIFTED EASTWARD ON TUESDAY AND TAPERED OFF BY
WEDNESDAY.
TEMPS UNDER THE MID/UPR TROUGH WERE FORECAST USING A GUIDANCE
BLEND AND WL REMAIN APPROXIMATELY 5 DEGREES BELOW NORMAL THROUGH
THE SHORT TERM PERIOD.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
CONSENSUS OF RECENT ECMWF AND NAEFS MODEL OUTPUT SHOW BROAD HIGH
PRESSURE ACROSS THE EASTERN U.S. WILL MAINTAIN DRY CONDITIONS
THROUGH FRIDAY IF NOT SATURDAY.
BLEND OF GFS MOS, ECMWF MOS, AND NAEFS MEDIAN VALUES SHOW
TEMPERATURES WEDNESDAY CAN STILL BE SLIGHTLY COOLER THAN NORMAL. AS
HIGH PRESSURE CENTER TRANSITIONS TO THE EAST COAST, DAYTIME HIGH
TEMPERATURES WILL BECOME SLIGHTLY WARMER THAN NORMAL THURSDAY INTO
WEEKEND.
BY SATURDAY, LOW LEVEL SOUTHERLY WINDS WILL TRANSPORT SURFACE DEW
POINTS OF 60 TO 65 INTO THE UPPER OHIO VALLEY. SO EARLY MORNING LOW
TEMPERATURES SHOULD RETURN TO NEAR NORMAL VALUES THIS WEEKEND.
CONCUR WITH HPC THINKING THAT THERE CAN BE AT LEAST A SLIGHT CHANCE
OF SHOWERS BY SUNDAY.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
EXPECT MAINLY VFR ACROSS THE UPPER OHIO VALLEY THROUGH 08Z
MONDAY. CANNOT COMPLETELY RULE OUT RESTRICTIONS AS SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS CAN BE POSSIBLE LATE THIS
AFTERNOON.
PER RECENT GFS LAMP AND NAM MOS, THERE IS POTENTIAL FOR AN IFR
RIVER VALLEY FOG EPISODE 08Z-13Z MONDAY. SO FAR HAVE SUFFICIENT
CONFIDENCE TO FORECAST MVFR VISIBILITIES AT NEARBY TAF SITES. THE
DEGREE OF EARLY MORNING FOG WILL ALSO DEPEND EXTENT OF RAINFALL
THIS AFTERNOON AND LATER RADIATIONAL COOLING RESULTING FROM
DECREASE IN CLOUDS TONIGHT.
.OUTLOOK/ SUNDAY NIGHT THROUGH THURSDAY/...
GENERALLY VFR. RESTRICTIONS MAY ACCOMPANY SCATTERED THUNDERSTORMS
MONDAY AFTERNOON AND EVENING AND PATCHY RIVER VALLEY FOG EACH
MORNING.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
333 PM EDT SUN AUG 19 2012
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 332 PM EDT SUN AUG 19 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER
ERN NAMERICA AND ARND CLOSED UPR LO NEAR JAMES BAY DOWNSTREAM OF UPR
RDG OVER THE ROCKIES. RUC ANALYSIS INDICATES A SHRTWV EMBEDDED
WITHIN THE UPR TROF IS OVER LK SUP. THIS DISTURBANCE/HINT OF SFC LO
PRES TROF SUPPORTED SOME SCT -SHRA MAINLY OVER CNTRL UPR MI INTO
EARLY AFTN. BUT DESPITE SOME SFC HEATING...THERE ARE NO MORE THAN
ISOLD -SHRA NOW OVER THE SCNTRL DESPITE SOME LK BREEZE CNVGC IN THAT
AREA. LLVL DRY AIR APPEARS TO BE THE MAIN LIMITING FACTOR AS SFC
DEWPTS HAVE MIXED OUT TO 40 TO 45 AT MOST SPOTS. ANOTHER STRONGER
DISTURBANCE ROTATING ARND THE PARENT UPR LO IS NOTED ON WV IMAGERY
OVER NRN ONTARIO. WHERE THE MSTR IS DEEPEST ON THE CYC SIDE OF THIS
FEATURE...THICK CLD COVER IS PRESENT OVER MUCH OF ONTARIO EXCEPT THE
FAR W. MUCH DRIER AIRMASS SHOWN ON THE 12Z INL/YPL RAOBS...WHERE
PWAT IS 0.38/0.41 INCH RESPECTIVELY OR NEAR 50 PCT OF NORMAL...IS
ALLOWING CLR-PCLDY CONDITIONS FM NRN MN THRU MOST OF WRN ONTARIO.
BUT THERE IS ANOTHER PATCH OF CLDS OVER FAR NW ONTARIO/ADJOINING
MANITOBA ASSOCIATED WITH YET ANOTHER SHRTWV DIVING SSEWD E OF LK
WINNIPEG WITHIN THE NNW FLOW ALF.
TONIGHT...EXPECT ANY LINGERING -SHRA OVER MAINLY THE SCNTRL TO END
THIS EVNG WITH EXIT OF SHRTWV NOW OVER LK SUP AND LOSS OF DAYTIME
HEATING. ALTHOUGH THE EVNG WL THEN TURN MOCLR EXCEPT FOR SOME PATCHY
HI CLDS WITH DRY AIR SHOWN ON THE 12Z INL/YPL RAOBS DOMINATING...
BULK OF GUIDANCE INDICATES SHRTWV NOW DIVING SWD THRU NRN ONTARIO WL
DIVE SWD TO NEAR ISLE ROYALE BY 12Z MON. SO EVEN THOUGH ALL MODELS
SHOW BULK OF THICKER CLD NOW DOMINATING MUCH OF ONTARIO ON THE CYC
SIDE OF SHRTWV TRACK WL REMAIN TO THE NE OF THE CWA UNDER LOWER H85
TEMPS...SUSPECT MORE CLDS WL ARRIVE OVER AT LEAST THE NRN TIER LATER
TNGT. WITH A PERIOD OF MOCLR SKIES THRU AT LEAST THE EVNG INTO EARLY
OVERNGT...EXPECT A QUICK DROP OF TEMPS. THE COOLEST OVERNGT MINS
INTO THE UPR 30S ARE MOST LIKELY OVER THE SRN TIER...WHERE MORE CLDS
ASSOCIATED WITH INCOMING SHRTWV ARE LIKELY NOT TO ARRIVE BEFORE
SUNRISE.
MON...INCOMING SHRTWV IS PROGGED TO SLIDE SWD ACRS WRN UPR MI AND
INTO WI IN THE AFTN. SINCE THE CWA WL BE ON THE CYC SIDE OF THE
TRACK OF THIS DISTURBANCE AND ACCOMPANYING DPVA/SOME DEEP LYR
QVECTOR CNVGC WL OCCUR DURING PEAK HEATING TIME...EXPECT AT LEAST
ISOLD -SHRA TO IMPACT MAINLY THE SCNTRL...WHERE SOME LK BREEZE CNVGC
MIGHT ENHANCE PCPN POTENTIAL. POPS WL BE LIMITED BY LLVL DRY AIR AND
LO KINX FCST NO HIER THAN 25 TO 30. WITH H85 TEMPS FCST IN THE 7 TO
9C RANGE...EXPECT HI TEMPS TO PEAK NOT FAR FM 70.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 332 PM EDT SUN AUG 19 2012
OVERALL GOOD MODEL AGREEMENT THROUGH WED...LEADING TO INCREASED
FORECAST CONFIDENCE FOR THIS TIME PERIOD.
STARTING THE PERIOD 00Z TUE...A SHORTWAVE TROUGH WILL BE EXITING THE
WA TO THE SE...ROTATING AROUND THE UPPER LEVEL LOW OVER NW QUEBEC
AND THE UPPER TROUGH OVER MUCH OF THE ERN HALF OF THE CONUS. THERE
MAY BE SOME SHOWERS EARLY ON MON NIGHT FROM THIS PASSING
THROUGH...BUT COVERAGE SHOULD BE LIMITED DUE TO THE DRY AIRMASS
OVERHEAD. WEAK UPPER RIDGING QUICKLY MOVES IN BEHIND THE
SHORTWAVE...EXTENDING FROM A RIDGE OVER THE WRN CONUS.
MODELS DO NOT SHOW ANY WAVES MOVING THROUGH ON TUE...BUT GIVEN NW
FLOW ALOFT IT IS HARD TO COMPLETELY RULE OUT AFTERNOON PRECIP...BUT
FOR NOW WILL LEAVE PRECIP OUT OF THE FORECAST. WITH ONLY SCATTERED
CU FOR CLOUDS...850MB TEMPS AOA 12MB SHOULD LEAD TO HIGH TEMPS IN
THE MID TO UPPER 70S...WITH A FEW LOW 80S POSSIBLE.
A WEAK SHORTWAVE TROUGH IS THEN SET TO MOVE NEAR THE CWA WED...ALSO
BRINGING A COLD FRONT INTO THE AREA. LIMITED MOISTURE AND
UNCERTAINTY REGARDING THE STRENGTH AND TRACK OF THE SHORTWAVE HAS
LEAD TO LIMITED CONFIDENCE WITH THIS SYSTEM...SO KEPT PRECIP CHANCES
ON THE LOW SIDE. HIGH TEMPS SHOULD BE SIMILAR TO TUE.
FOR WED NIGHT THROUGH NEXT SUN...MODELS SHOW THE COLD FRONT FROM WED/WED
NIGHT STALLING OVER OR NEAR THE CWA THU THROUGH FRI UNTIL AN
UPPER/SFC TROUGH MOVE THROUGH FRI NIGHT AND SAT. MODELS ALSO SHOW A
STRONGER UPPER LOW MOVING ACROSS SRN CANADA STARTING WED
NIGHT...THEN MOVING TO MANITOBA BY 00Z NEXT MON. WHEREAS THE 00Z/19
GFS AND 00Z/19 ECMWF AGREE PRETTY WELL ON THE LARGE SCALE
PATTERN...THE ECMWF HAS HAD VERY POOR RUN TO RUN CONTINUITY. THE GFS
ON THE OTHER HAND HAS SHOWN FAIRLY GOOD RUN TO RUN
CONTINUITY...LEADING TO MORE CONFIDENCE IN THE GFS SOLUTION BUT LOW
FORECAST CONFIDENCE OVERALL FOR THU ON. DID NOT SPEND TOO MUCH TIME
ON THIS PART OF THE FORECAST GIVEN LIMITED CONFIDENCE...AND SINCE
CONSENSUS OF MODEL DATA /WHICH FAVORS THE GFS/ LOOKED
REASONABLE...SO JUST USED THAT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 136 PM EDT SUN AUG 19 2012
ALTHOUGH DISTURBANCES ROTATING ARND DEEP CLOSED LO NEAR JAMES BAY
WILL BRING PERIODS OF CLDS TO UPR MI THIS FCST PERIOD...EXPECT VFR
CONDITIONS TO PREVAIL WITH RELATIVELY DRY NEAR SFC LYR. ALTHOUGH
THERE COULD BE SOME FOG MAINLY AT SAW/IWD TNGT WITH LIGHT WINDS
UNDER WEAK SFC HI PRES RDG...NO FOG WAS OBSVD UPSTREAM LAST NGT
WITHIN DRY AIRMASS DEPICTED ON THE 12Z INL/YPL RAOBS. SO KEPT A
MENTION OF FOG OUT OF TAFS FOR NOW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 332 PM EDT SUN AUG 19 2012
EXPECT WINDS NO HIER THAN 20 KTS THRU THU WITH WEAK PRES GRADIENT
DOMINATING THE UPPER GREAT LAKES. SINCE HI PRES WILL DOMINATE MOST
OF THE TIME UNTIL LATER IN THE WEEK...THERE WILL BE LITTLE THREAT OF
PRECIPITATION UNTIL THU.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
137 PM EDT SUN AUG 19 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 507 AM EDT SUN AUG 19 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP TROF DOMINATING THE
ERN CONUS. TROF CONTINUES TO BE ANCHORED BY A MID/UPPER LEVEL
CYCLONE CENTERED IN THE VCNTY OF JAMES BAY...AND THE UPPER LAKES ARE
FIRMLY UNDER THE INFLUENCE OF THE TROF. ALTHOUGH SHORTWAVE AND
ASSOCIATED COLD FRONT PASSED YESTERDAY AFTN/EVENING...VARYING
AMOUNTS OF CLOUD COVER LINGER OVER UPPER MI EARLY THIS MORNING. OCNL
CLOUD COVER IS PROBABLY PREVENTING A MORE WIDESPREAD OR DENSE FOG
FROM DEVELOPING AS SEVERAL SITES HAVE HAD WIDELY FLUCTUATING VIS
DURING THE NIGHT.
WITH UPPER MI REMAINING FIRMLY UNDER THE INFLUENCE OF THE MID/UPPER
TROF TODAY AND TONIGHT...MAIN FCST ISSUE IS WHETHER ANY PCPN WILL
OCCUR. IN SUMMERTIME NW FLOW...EVEN THE SUBTLEST OF WAVES CAN
TRIGGER ISOLD/SCT CONVECTION. WHILE THERE ARE NO OBVIOUS SHORTWAVES
EVIDENT UPSTREAM IN NRN ONTARIO...THERE ARE HINTS OF ONE JUST N OF
LAKE SUPERIOR THAT IS ANALYZED BY THE LATEST RUC. THAT SUBTLE WAVE
IS PROBABLY RESPONSIBLE FOR THE RECENT EXPANSION OF CLOUDS OVER THE
FCST AREA AS WELL AS THE ISOLD SHRA THAT HAVE DEVELOPED FROM
ONTONAGON COUNTY N TO JUST OFFSHORE OF THE KEWEENAW PENINSULA. ONE
ASPECT THAT WILL BE WORKING AGAINST CONVECTION TODAY WILL BE THE
DRIER AIR MASS EVIDENT UPSTREAM IN NRN ONTARIO PER 00Z CWPL
SOUNDING. AS AN INDICATION OF THE DRIER AIR...THE K INDEX WAS 3. A
NICE SWATH OF CLEAR SKIES WAS ALSO EVIDENT ACROSS NRN ONTARIO TO THE
NW OF LAKE SUPERIOR YESTERDAY AFTN...AND SFC DWPTS WERE DOWN INTO
THE 30S IN THAT AREA. HOWEVER...WITH AFORMENTIONED SUBTLE WAVE
DRIFTING S...DEVELOPMENT OF LAKE BREEZE CONVERGENCE ZONE BTWN LAKE
SUPERIOR AND LAKE MI AND WITH MODELS DELAYING ARRIVAL OF THE DRIER
AIR UPSTREAM...A MENTION OF AT LEAST ISOLD SHRA APPEARS WARRANTED
FROM ROUGHLY NEAR KIMT E TO S OF KERY IN THE LAKE BREEZE CONVERGENCE
ZONE THIS AFTN. WILL ALSO NEED TO MONITOR TRENDS OVER THE NEXT FEW
HRS TO SEE IF CURRENT EXPANDING CLOUD COVER IS A PRECURSOR TO
MORNING SHRA DEVELOPMENT OVER A LARGER PORTION OF THE FCST AREA.
ANY SHRA NEAR LAKE MI WILL END EARLY THIS EVENING AS SHORTWAVE SLIPS
TO THE S. OTHERWISE...IT SHOULD BE A DRY NIGHT THOUGH THERE ARE
HINTS THAT ANOTHER WAVE MAY BE DROPPING INTO THE AREA OVERNIGHT.
WILL BE SOMETHING TO MONITOR FOR POSSIBLY ADDING SLIGHT CHC/ISOLD
SHRA IN LATER FCSTS. POTENTIAL CLOUD COVER WITH WEAK WAVE MAKES FOR
A CHALLENGING MIN TEMP FCST TONIGHT. AT THIS TIME...IT APPEARS CLOUD
COVER SHOULD BE LIMITED ENOUGH FOR AT LEAST THE FIRST PART OF THE
NIGHT TO FAVOR THE LOWER END OF AVBL GUIDANCE. SOME UPPER 30S WILL
BE POSSIBLE IN TRADITIONAL INTERIOR COLD SPOTS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 507 AM EDT SUN AUG 19 2012
GENERAL AGREEMENT IS PRESENT IN OVERALL UPPER AIR PATTERN THROUGH
THE UPCOMING WEEK. DEEP TROUGH OVER MOST OF EASTERN CANADA INTO THE
EASTERN CONUS /INCLUDING GREAT LAKES/ DE-AMPLIFIES BY WEDNESDAY. BY
THE MID-LATE WEEK...TROUGH OVER WESTERN CANADA INTO PACIFIC NORTHWEST
EJECTS A PIECE OF ENERGY INTO THE NORTHERN PLAINS. WHERE THAT WEAKER
TROUGH PROGRESSES IS A QUESTION AND WILL HAVE IMPACT ON FORECAST OVER
UPPER GREAT LAKES THURSDAY AND FRIDAY. FAIR TO SAY THAT AGREEMENT
FROM THE GFS/ECMWF/GEM-NHEM IS BETTER TO START THE WEEK THAN TO END
THE WEEK. MAIN ISSUE AT END OF WEEK IS HOW FAR EAST ENERGY OVER THE
NORTHERN PLAINS WILL MOVE INTO THE GREAT LAKES. GFS CONTINUES TO BE
DEEPER AND FARTHER EAST...RESULTING IN GOOD CHANCE OF PRECIPITATION
ON FRIDAY OVER UPPER MICHIGAN. ECWMF/EXTRAPOLATION OF GEM-NHEM WOULD
KEEP MAJORITY OF FORCING AND PRECIPITATION WITH THE WEAKER TROUGH
SOUTHWEST OF UPPER MICHIGAN INTO THE UPPER MISSISSIPPI RIVER VALLEY.
TO START THE LONG TERM...HAVE A SMALL SHOT AT ISOLD SHRA ON MONDAY
OVER CENTRAL CWA IN THE MID-LATE AFTERNOON AS LAST OF STRONGER
SHORTWAVES DROP SOUTH ON WESTERN PERIFERY OF LARGER SCALE UPPER
TROUGH. FORECAST SOUNDINGS FROM GFS AND NAM INDICATE MOISTURE OVER
THE CWA ONLY FOCUSES BETWEEN 800MB AND 700MB. DRY AIR BELOW LCL
IS QUITE DRY AS DAY BEGINS WITH DEWPOINTS IN THE 30S. PROBABLY WILL
ONLY SEE DEWPOINTS RISE INTO THE MID 40S AT BEST IN THE AFTERNOON AS
LOW-LEVEL MOISTURE ADVECTION IS LIMITED. SREF IDEA SHOWING QPF
FORMING OVER SCNTRL CWA AFTER 18Z IS LIKELY ON TRACK. COVERAGE OF ANY
SHRA WILL BE VERY ISOLATED DUE TO DRY LOW-LEVELS. NO TSRA INCLUDED
WITH POOR MID-LEVEL LAPSE RATES LESS THAN 6C/KM AND SBCAPE VALUES
ONLY UP TO 200 J/KG. MODELS HINT AT MID-LEVEL MOISTURE STICKING
AROUND OFF AND ON THROUGH MONDAY NIGHT BUT WITH SAME LIMITING FACTORS
AS MONDAY AFTERNOON DO NOT EXPECT MUCH IN WAY OF PRECIPITATION ON
MONDAY NIGHT.
COUPLE OF WEAKER SHORTWAVES RIPPLE THROUGH UPPER GREAT LAKES TUESDAY
BUT MOISTURE IS FORECAST TO BE EVEN SHALLOWER THAN ON MONDAY...AGAIN
CENTERED AROUND 800MB. ADDITIONAL MID-LEVEL MOISTURE COULD ROLL
ACROSS WITH SCT-BKN CLOUDS 15-20 KFT POSSIBLE. MIX OF CLOUDS AND
SUNSHINE GIVES WAY TO MORE SUNSHINE IN THE AFTERNOON...SO BASED ON
H85 TEMPS TOWARD AOA 12C EXPECT MAX TEMPS WELL INTO THE 70S FOR MOST
AREAS WITH EVEN A POTENTIAL OF SEEING SOME READINGS AROUND 80
DEGREES OVER WESTERN AND CENTRAL CWA.
LOOKING WELL TO THE NORTHWEST CURRENTLY THERE IS A PRETTY STRONG
SHORTWAVE CRESTING RIDGE OVER WESTERN CONUS INTO WESTERN CANADA.
WAVES IS OVER THE NORTHWEST TERRITORIES OF CANADA. MODELS SHOW WAVE
SPLITTING BUT ONE FORMIDABLE PIECE OF SHORTWAVE ENERGY IS FORECAST
TO DIG INTO NORTHWEST ONTARIO TUESDAY NIGHT INTO WEDNESDAY. GFS
FARTHER SOUTH WITH THE WAVE AND ASSOCIATED PRECIPITATION...BUT
ECMWF AND GEM-NHEM HAVE THE WAVE AS WELL...BUT NOT AS FAR SOUTH. NAM
APPEARS TOO FAST/WEAK WITH THE SHORTWAVE AND IS NOT PREFERRED. ALL
THE MODELS INDICATE AREA OF H85 TEMP AND H85-H7 MOISTURE ADVECTION
SETS UP JUST AHEAD OF THE WAVE AS IT DIGS TOWARD UPPER GREAT LAKES
TUESDAY NIGHT. USING BLEND OF LAST FEW GFS MODEL RUNS ALONG WITH
ECMWF/GEM-NHEM AND EVEN SOME OF THE SREF...KEPT POPS HIGHEST ON
TUESDAY NIGHT OVER NORTHERN SECTIONS OF LK SUPERIOR...AND NO REAL
POPS OVER LAND AREA OF UPPER MICHIGAN...ASIDE FROM ISLE ROYALE.
IDEA FITS SYNOPTIC PATTERN AS MOST LAND CWA WILL BE THE WITHIN THE
MORE UNFAVORABLE RIGHT EXIT REGION OF JET STREAK FOR PRECIPITATION.
KEPT SLIGHT CHANCES FOR WEDNESDAY OVER CENTRAL AND EAST AS LARGER
SCALE FORCING ALONG WITH WEAK SFC TROUGH COULD COMBINE WITH DAYTIME
HEATING TO HELP FORM SOME SHOWERS DURING THE PEAK HEATING OF THE DAY.
IN THE EXTENDED...00Z MODEL RUNS PROVIDE NO TRENDS OF NOTE ON EXTENT
OF LARGER SCALE TROUGHING OVER UPPER GREAT LAKES TO CLOSE THE WEEK.
GFS CONTINUES TO SHOVE UPPER TROUGH PUSHING INTO THE NORTHERN PLAINS
ON THURSDAY ON INTO THE UPPER GREAT LAKES ON FRIDAY. THE TROUGH ALONG
WITH INCREASING LOW-LEVEL MOISTURE ADVECTION AND PRESENCE OF SFC WARM
FRONT HELPS TO GENERATE PLENTY OF QPF FRIDAY INTO FRIDAY NIGHT. ON
THE FLIP SIDE THE LATEST ECMWF IS MORE SHUNTED TO THE SOUTHWEST WITH
THE UPPER TROUGH AND THUS BRINGS VERY LITTLE QPF INTO THE UPPER GREAT
LAKES WITH HIGH PRESSURE STAYING THE DOMINANT FEATURE. MAIN WARM
FRONT REMAINS WELL TO THE SOUTH OF CWA. LATEST CANADIAN LOOKS MORE
LIKE THE ECMWF BUT DOES TRY TO BRING SOME QPF INTO AT LEAST WESTERN
CWA ON FRIDAY. MODEL CONSENSUS INDICATES HIGHEST CHANCES FOR
PRECIPITATION FRIDAY INTO FRIDAY NIGHT...BUT THIS IS BEING BIASED
SOMEWHAT BY GFS MODEL ELEMENTS. WILL STAY WITH CONSENSUS GIVEN THE
STARK DIFFERENCES OFFERED UP BY ECMWF AND GFS...BUT CERTAINLY
POSSIBLE THAT FRIDAY MAY END UP MAINLY DRY COMPARED TO THE HIGHER
CHANCE POPS IN THIS FORECAST. DOES APPEAR THAT NEXT WEEKEND WOULD
FEATURE A DRYING TREND AS THE UPPER TROUGH DEPARTS THE AREA. TOUGH TO
GET TOO SPECIFIC ABOUT THOSE DETAILS THOUGH DUE TO THE MODEL
DIFFERENCES STILL AROUND LEADING INTO NEXT WEEKEND. TEMPERATURES
SHOULD SHOW WARMING TREND INTO NEXT WEEKEND AS H85 TEMPS STEADILY
CLIMB FROM WEDNESDAY TO SATURDAY. IF GFS IS CORRECT THOUGH...WARMING
WOULD BE TEMPERED THURSDAY AND DEFINITELY INTO FRIDAY WITH MORE
CLOUDS AND PRECIPITATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 136 PM EDT SUN AUG 19 2012
ALTHOUGH DISTURBANCES ROTATING ARND DEEP CLOSED LO NEAR JAMES BAY
WILL BRING PERIODS OF CLDS TO UPR MI THIS FCST PERIOD...EXPECT VFR
CONDITIONS TO PREVAIL WITH RELATIVELY DRY NEAR SFC LYR. ALTHOUGH
THERE COULD BE SOME FOG MAINLY AT SAW/IWD TNGT WITH LIGHT WINDS
UNDER WEAK SFC HI PRES RDG...NO FOG WAS OBSVD UPSTREAM LAST NGT
WITHIN DRY AIRMASS DEPICTED ON THE 12Z INL/YPL RAOBS. SO KEPT A
MENTION OF FOG OUT OF TAFS FOR NOW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 507 AM EDT SUN AUG 19 2012
BRIEFLY TIGHTER PRESSURE GRADIENT WILL ALLOW NORTHWEST WIND GUSTS
TO REACH 20-25 KTS OVER EASTERN SECTIONS OF LK SUPERIOR THIS
AFTERNOON INTO THIS EVENING. WINDS DIMINISH OVERNIGHT TONIGHT AND
REMAIN MAINLY BELOW 20 KTS THROUGH WEDNESDAY AS HIGH PRESSURE STAYS
CLOSE BY. EXCEPTION COULD BE TUESDAY AFTERNOON AND EVENING OVER
WESTERN SECTIONS WITH SOUTHWEST WIND GUSTS PUSHING ABOVE 20 KTS IN
THE VICINITY OF ISLE ROYALE. LOW PRESSURE SYSTEM APPROACHING LATE
THIS WEEK RESULTS IN WINDS BECOMING MORE EAST TO SOUTHEAST AND
INCREASING OVER 20 KTS. WINDS MAY END UP HIGHER DEPENDING ON
ULTIMATE TRACK AND STRENGTH OF SURFACE LOW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...KC
MARINE...JLA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
141 PM CDT SUN AUG 19 2012
.UPDATE...
UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.
&&
.DISCUSSION...
RATHER AMPLIFIED UPPER AIR PATTERN REMAINS IN PLACE THIS
MORNING...WITH SHARP UPPER RIDGE UP THE ROCKY MOUNTAINS FLANKED
BY A DEEP CLOSED LOW NEAR HUDSON BAY AND A LONGWAVE TROUGH OVER
THE NERN PAC. WITHIN THE NNW FLOW OVERHEAD...WATER VAPOR IMAGERY
AND RAP PV ANALYSIS SHOWS A POTENT WAVE DROPPING INTO CENTRAL MN
AT 8Z. AT THE SFC...HIGH PRESSURE WAS PARKED ACROSS MUCH OF THE
GREAT PLAINS WITH A WEAK FRONT/WIND SHIFT STILL EVIDENT IN THE FLOW
FROM MADISON...MN ACROSS THE TWIN CITIES AND OVER TOWARD GREEN
BAY.
ALOFT...PATTERN WILL UNDERGO A SLOW DE-AMPLIFICATION OVER THE
COMING DAYS. BY THE MIDDLE OF NEXT WEEK...WEAK ZONAL FLOW WILL BE
IN PLACE ACROSS MUCH OF THE CONUS AS ROCKIES RIDGE FLATTENS
OUT...THE HUDSON LOW FILLS/LIFTS NE AND THE PAC TROUGH MOVES INTO
BC AND UNDERGOES SOME DEEPENING. MEDIUM RANGE MODELS DO NOT BRING
THE WRN WAVE ACROSS THE CENTER OF THE CONTINENT UNTIL NEXT
WEEKEND.
AT THE SFC...FRONT SPLITTING THE MPX CWA NEARLY IN HALF THIS
MORNING WILL SLOWLY WASH OUT DURING THE DAY AS HIGH PRESSURE ACROSS
THE DAKOTAS PUSHES EAST. THIS HIGH PRESSURE WILL THEN SLOWLY TRACK
ACROSS THE UPPER MS VALLEY THROUGH TUESDAY NIGHT. WEDNESDAY...A
WEAK FRONTAL BOUNDARY WILL TRY TO SAG INTO THE LAKE SUPERIOR
REGION AS A LEE THROUGH SLOWLY TAKES SHAPE ACROSS THE HIGH PLAINS AS
UPPER FLOW BECOMES MORE ZONAL. THE FIRST FRONTAL PUSH FROM THIS
LEE TROUGHING LOOKS TO TRY AND PUSH INTO THE MPX AREA
THU/FRI...WITH A MORE SIGNIFICANT FRONT NOT LIKELY TO ARRIVE UNTIL
NEXT WEEKEND WITH THE STRONGER UPPER FORCING.
FOR TODAY THERE ARE TWO CONCERNS THANKS TO SHORTWAVE NOW IN
CENTRAL MN. FIRST IS HOW FAR NORTH TO KEEP POPS TODAY...WHILE THE
SECOND IS WHAT IMPACT WILL CLOUDS HAVE ON MAX TEMPS. FOR
PRECIP...TRIED LIMITING MENTIONABLE PRECIP TO WHERE MODELS SHOW
K-INDEX EXCEEDING 28. GOING BACK TO YESTERDAY...THIS MATCHED UP
FAIRLY WELL WITH WHERE SHOWERS/STORMS WERE ABLE TO FIRE OFF.
THOUGH MODELS DIFFER ON HOW QUICKLY THE H7 THROUGH/MOISTURE MAKE
IT THROUGH THE REGION...THEY ARE ALL FAIRLY SIMILAR WITH THEIR
K-INDEX FORECASTS...WHICH MATCHES UP WELL WITH 19.03 SREF PROBS.
HAVE HIGHEST POPS ACROSS SOUTH CENTRAL MN THIS MORNING...WITH ISO
STORMS LINGERING INTO THE AFTERNOON ALONG I-90. HOWEVER...THERE
IS SUPPORT FROM THE 19.00 ECMWF/GFS ALONG WITH HRRR REFLECTIVITY
FORECASTS FOR HAVE POPS FARTHER NORTH THAN CURRENTLY INDICATED FOR
TODAY. IF THE GFS/ECMWF ENDS UP BEING THE ROUTE THINGS TAKE FOR
TODAY...THEN IT WILL LIKELY END BEING MOSTLY CLOUDY ACROSS SOUTH
CENTRAL MN...WHERE HIGHS COULD END UP SEVERAL DEGREES COOLER THAN
CURRENTLY INDICATED.
PRECIP WILL QUICKLY CUT OFF THIS EVENING...WITH SKIES BECOMING
CLEAR. THIS WILL SET THE STAGE FOR RATHER TRANQUIL WEATHER FOR
SUNDAY THROUGH WEDNESDAY AS THE SFC HIGH SLOWLY SLIDES EAST. WITH
H5 HEIGHTS AND H85 TEMPS SLOWLY BUILDING DURING THIS PERIOD...WILL
SEE HIGHS TICK UP A COUPLE OF DEGREES EACH DAY. BY WEDNESDAY...THE
RETURN OF SOUTHERLY FLOW WILL HELP BOAST TEMPS BACK INTO THE
LOWER 80S...ALONG WITH SENDING DEWPS BACK INTO THE 60S.
FOR WEDNESDAY NIGHT THROUGH FRIDAY...UNCERTAINTY IN THE FORECAST
INCREASES QUITE A BIT. THOUGH THE MEDIUM RANGE MODELS GENERALLY
AGREE ON WEAK ZONAL FLOW SETTING UP ACROSS THE NRN CONUS THIS
PERIOD...THEY DIFFER ON THE HANDLING OF A SHORT WAVE PEGGED TO
MOVE THROUGH THIS FLOW FROM THURSDAY INTO FRIDAY. THE GFS
CONTINUES TO BE THE MOST AGGRESSIVE WITH THE WAVE...BRINGING A
NEGATIVELY TILTED SHORTWAVE AND ASSOCIATED COLD FRONT ACROSS THE
AREA THURSDAY NIGHT INTO FRIDAY. THE ECMWF SHOWS A MUCH
WEAKER/SLOWER WAVE WORKING INTO THE PLAINS...WITH VERY LITTLE IN
THE WAY OF PRECIP WORKING INTO THE AREA UNTIL THE WEEKEND FRONT.
FOR THIS PERIOD...FOLLOWED THE BLEND APPROACH WITH THE CONTINUED
MENTION OF 40-50 POPS THURSDAY NIGHT. HARD TO SAY WHICH WAY THINGS
MAY GO AT THIS POINT...BUT IT DOES APPEAR THE GFS IS SUFFERING
FROM SOME CONVECTIVE FEEDBACK WHICH IS LIKELY IMPACTING THE
STRENGTH OF SFC FEATURES IT SHOWS.
&&
.AVIATION.../00Z TAF ISSUANCE/
VFR FOR THIS TAF SET. CDFNT NOW S OF MN AND INTO FAR SRN WI WILL
CONTINUE TO PUSH OFF TO THE S AND E THRU TNGT...BEING REPLACE BY
INCOMING HIGH PRES. GENERALLY FAIR WX CUMULUS CLOUD DEVELOPMENT
THIS AFTN BUT ONE POTENTIAL PROBLEM MAY BE ISOLD SHWRS NEAR THE
IA/MN BORDER LATE THIS AFTN INTO EARLY THIS EVE. SHORT-TERM MODELS
INDICATE ISOLD TO SCATTERED SHOWER DEVELOPMENT...IN RESPONSE TO
THE WOBBLING CDFNT AND A SHORTWAVE TROUGH AXIS SWINGING AROUND THE
PERIPHERY OF A DEPARTING UPPER LEVEL LOW. ONLY KRWF LOOKS
SUSCEPTIBLE TO SHOWERS WHILE ALL OTHER TAF SITES REMAIN DRY. SKIES
CLEAR OUT BY LATE EVENING AND WILL REMAIN CLEAR THRU TMRW AFTN.
MAINLY N WINDS...DROPPING OFF OVERNIGHT THEN PICKUP UP ONCE AGAIN
TMRW...LESS THAN 10 KT.
KMSP...VFR THROUGHOUT WITH VERY LITTLE AVIATION CONCERNS.
SCATTERED FAIR WX CUMULUS DEVELOPMENT THIS AFTN WILL GIVE WAY TO
CLEAR SKIES TNGT THRU TMRW. MAINLY N WINDS IN THE 5-9 KT RANGE
THIS AFTN...DROPPING OFF TONIGHT THEN PICKING UP AGAIN TMRW.
/OUTLOOK FOR KMSP/
MON NIGHT...VFR. LIGHT/VARIABLE WINDS.
TUE...VFR. SOUTHWEST 5 TO 10 KT.
WED...VFR. SOUTH 5 TO 10 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JPC
AREA FORECAST DISCUSSION
NWS ELKO NV
320 PM PDT SUN AUG 19 2012
.SYNOPSIS...MONSOON MOISTURE WILL CONTINUE TO PRODUCE SCATTERED
THUNDERSTORMS ACROSS NEVADA THROUGH THIS EVENING. DRIER AIR
ARRIVES IN NORTHERN NEVADA ON MONDAY...RESTRICTING THUNDERSTORM
COVERAGE TO AREAS SOUTH OF HIGHWAY 50. A SIGNIFICANT ROUND OF
THUNDERSTORMS IS EXPECTED ACROSS EASTERN NEVADA TUESDAY AFTERNOON
AND EVENING.
&&
.SHORT TERM...TONIGHT THROUGH TUESDAY. THUNDERSTORMS PRETTY MUCH
FOLLOWING THE EXPECTED SCRIPT THIS AFTERNOON...FAVORING THE
WESTERN AND SOUTHERN ZONES. INSTABILITY IS STRONGEST ACROSS HUMBOLDT
AND WHITE PINE COUNTIES...AND THESE ARE THE AREAS THAT WILL SEE
THE STRONGEST CONVECTION INTO THIS EVENING. EXPECT SHOWER AND
THUNDERSTORMS TO CONTINUE THROUGH THE EARLY EVENING...AS SHOWN BY
12/18Z NAM AND HRRR SOLUTIONS. WITH PRECIPITABLE WATER NEAR OR
ABOVE 1 INCH...AND K INDEX NEAR 40 WILL MAINTAIN FLASH FLOOD WATCH
FOR CENTRAL NEVADA THROUGH 8 PM. KLRX REFLECTIVITY INDICATES
HEALTHY NE MOVEMENT WITH THE STORMS...BUT WITH SUCH HIGH MOISTURE
CONTENT AND THE POTENTIAL FOR TRAINING ECHOES...WILL LET THE FLASH
FLOOD WATCH CONTINUE. ATMOSPHERE IS PLENTY MOIST...BUT RATHER
LIMITED ON INSTABILITY. REACHING CONVECTIVE TEMPERATURES HAS BEEN
DELAYED SOMEWHAT BY CLOUDS/SHOWERS/MORE STABLE AIR...BUT FEEL
CONVECTION WILL EXPAND INTO THE EVENING. STRONG STORMS AND LOCAL
FLOODING POSSIBLE. EXPECT THUNDERSTORM COVERAGE TO QUICKLY WANE
AFTER SUNSET AS USUAL.
MONDAY...SHORTWAVE RIDGE QUICKLY BUILDS OVER NEVADA...AND MUCH
DRIER AIR INVADES THE NORTHERN ZONES. PW FALLS TO WELL BELOW 0.50
INCH ACROSS ELKO COUNTY. THUNDERSTORM COVERAGE WILL BE RESTRICTED
TO ISOLATED MONDAY...AND CONFINED TO AREAS SOUTH OF U.S. HIGHWAY
50. THE REST OF US MOSTLY SUNNY AND HOT...WITH HIGHS IN THE LOWER
TO MID 90S.
MONDAY NIGHT...MONSOON MOISTURE SURGES QUICKLY NORTHWARD OVERNIGHT
BEHIND DEPARTING RIDGE AXIS...AND AHEAD OF TROUGH APPROACHING FROM
THE WEST. INCREASED CLOUDS AND SHOWER COVERAGE OVERNIGHT...WITH
VERY MILD LOW TEMPERATURES IN THE UPPER 50S AND LOWER 60S TUESDAY
MORNING.
TUESDAY...ACTIVE THUNDERSTORM DAY EXPECTED AHEAD OF APPROACHING
TROUGH...BUT ONLY ACROSS EASTERN NEVADA. MODELS CONTINUE TO
DEPICT AN EXTREMELY TIGHT MOISTURE GRADIENT ACROSS NEVADA...WITH
PW RANGING FROM 1.17 INCH NEAR WENDOVER...DOWN TO LESS THAN 0.25
INCH NEAR WINNEMUCCA. SCATTERED TO NUMEROUS THUNDERSTORMS EXPECTED
TO DEVELOP OVER EASTERN NEVADA /PRIMARILY ELKO AND WHITE PINE
COUNTIES/ TUESDAY AFTERNOON...AHEAD OF A QUASI-DRYLINE THAT WILL
BISECT THE CWA AT PEAK HEATING. CAPE AND BULK SHEAR VALUES WILL
ORGANIZE CONVECTION ACROSS EASTERN NEVADA...AND JET DYNAMICS FROM
APPROACHING TROUGH WILL HELP AS WELL. WITH THE CONSISTENCY IN
MODEL SOLUTIONS...WENT AHEAD AND ADDED WIND/HAIL WORDING TO THE
ZONES FOR EASTERN NEVADA TUESDAY. WESTERN NEVADA BONE DRY IN THE
DRY SLOT...WITH A VERY TIGHT GRADIENT IN THE POP GRIDS. EXPECT
SW TO W WINDS TO INCREASE TO AT LEAST BREEZY LEVELS...AS 700 MB
WINDS INCREASE TO NEAR 20 KTS. BT
.LONG TERM...TUESDAY NIGHT THROUGH NEXT SUNDAY. GENERAL AGREEMENT IN
THE MODELS THROUGH THE PERIOD...WITH JUST SOME SUBTLE DIFFS LATE IN
THE WEEK. OVERALL...DRYING AND A LITTLE COOLING...AT LEAST NOT IN
THE UPPER 90S ANY MORE. PERIOD BEGINS WITH THE LEFT OVERS OF THE
SERIOUS TROUGH ON TUESDAY MOVING OUT...AND SOME RESIDUAL CONVECTION
SMACK ALONG THE UTAH LINE TUESDAY NIGHT. BY WEDNESDAY MORNING THE
AIR MASS HAS DRIED OUT. A VERY WEAK QUASI-MONSOONAL PUSH OCCURS
EARLY THURSDAY BUT THE MODELS HAVE IT GETTING ONLY TO SOUTHEAST
WHITE PINE COUNTY. SOME LITTLE INSTABILITY THERE SO KEPT CONVECTION
IN A LIMITED AREA THERE. BY THURSDAY NIGHT THE ATMOSPHERE DRIES OUT
FURTHER AND THERE ARE VERY LOW TO ZERO POPS THE REST OF THE PERIOD.
ANOTHER LITTLE SHORT WAVE WITH ASSOCIATED SURFACE WIND SHIFT LATE
THURSDAY/EARLY FRIDAY WHICH WILL KEEP HIGHS IN THE UPPER 80S OR LOW
90S OVER MOST OF THE AREA. LOWS WILL BE IN THE 40S AND 50S...WITH A
FEW 30S OVER HIGHER TERRAIN...ESPECIALLLY IN THE NORTH. BB
&&
.AVIATION...CONVECTION WILL BEGIN TO WEAKEN WITH SUNSET OVER THE
GREAT BASIN AND STORMS WILL BECOME ISOLATED AT BEST AFTER 06Z. A FEW
SHOWERS WILL STILL AFFECT CENTRAL AND EASTERN NEVADA THROUGH 12Z.
WILL KEEP VCTS AT KWMC...KTPH...AND KELY...AND VCSH AT KEKO THROUGH
03Z. WILL KEEP VCSH AT KELY THROUGH 06Z. WINDS WILL DROP TO
UPSLOPE/DOWN VALLEY AND LIGHT SPEEDS. BB
&&
.FIRE WEATHER...SCATTERED THUNDERSTORMS ACROSS THE FIRE DISTRICT
THROUGH SUNSET THIS EVENING. ELEVATED LAL...BUT MOST STORMS WILL
PRODUCE ENOUGH RAINFALL TO LIMIT NEW LIGHTNING IGNITIONS.
MONDAY...DRIER AIR ACROSS THE NORTHERN FWZ. THUNDERSTORM COVERAGE
WILL BE LIMITED TO ISOLATED...AND CONFINED TO AREAS SOUTH OF U.S.
HIGHWAY 50.
TUESDAY...SCATTERED TO NUMEROUS THUNDERSTORMS EXPECTED ACROSS
EASTERN NEVADA...PRIMARILY FWZ 455...469...470. STRONG STORMS WITH
GUSTY ERRATIC OUTFLOW WINDS ARE POSSIBLE. BT
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM PDT THIS EVENING FOR NORTHEASTERN
NYE COUNTY...NORTHWESTERN NYE COUNTY...SOUTHERN LANDER COUNTY
AND SOUTHERN EUREKA COUNTY...WHITE PINE COUNTY.
&&
$$
99/98/98/99
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
211 PM EDT SUN AUG 19 2012
.SYNOPSIS...
A SLOW MOVING FRONT...IN COMBINATION WITH AN UPPER LEVEL
DISTURBANCE...WILL BRING THE CHANCE FOR SHOWERS AND ISOLATED
THUNDERSTORMS TO THE REGION LATER TONIGHT INTO MONDAY EVENING. HIGH
PRESSURE WILL BUILD INTO THE REGION STARTING ON TUESDAY WITH FAIR
WEATHER EXPECTED FOR MID WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
SFC ANYLS SHOWS A CDFNT ACRS LOWER ONTARIO INTO CNTRL MI WITH AN
INVERTED TROF DVLPNG OVER ERN OH/WRN PA. AT UPR LVLS...THE DEEP TROF
OVER THE ERN U.S. WILL GRADUALLY LIFT NEWD/PULL OUT...WITH MDLS
SUGGESTING THE CDFNT/INVERTED TROF WILL EVENTUALLY MERGE AND WORK EWD
ACRS THE BGM FCST AREA ON MON...AS LOW PRES TRACKS NEWD OFF THE MID
ATLC CST. THE MAIN TROF AXIS WON`T PASS THE FCST AREA TIL
WED....WITH UPR FLOW BCMG GNRLY ZONAL BY WED EVNG.
GRADUAL MOISTENING WILL OCCUR OVRNGT AS SRLY FOW DVLPS AHEAD OF THE
SFC TROF/FNT. SHORT RNG MESO MDLS INCLUDING THE RUC AND LCL WRF SUGGEST
THAT ACTIVITY ACRS CNTRL PA COULD TRACK NWD INTO THE CNTRL SRN
TIER THIS EVNG ALONG AND EAST OF THE SFC TROF...AND HINTS THAT
ADDNL ISOLD/WDLY SCT DVLPMNT IS PSBL...SO WE INDICATE LOW CHC POPS
SPREADING N AND NE ACRS THE FCST AREA OVRNGT.
ANOTHER S/WV IS FCST TO APRCH THE RGN TMRW AFTN...AND THIS IN
COMBINATION WITH THE SFC BNDRY SHUD HELP TO FOCUS ACTIVITY ACRS
CNTRL/ERN ZONES ON MON AFTN. CHCS FOR TSRA WILL BE ON THE LOW SIDE
GIVEN LIMITED INSTABILTY. TEMPS COULD BE TRICKY ON MON...FOR NOW
INDICATED COOLEST MAXES ACRS SE ZONES (A70 OR L70S).
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
SHRA ARE XPCTD TO DIMINISH/MOV OUT ON MON EVNG. MDLS SUGGEST
POTNL FOR ISOLD ACTIVITY FAR SRN TIER AND NE PA ON TUE AND PSBLY WED.
OVERALL THE PTRN DOES NOT LOOK AS FVRBL FOR DIURNAL CONVECTIVE
DVLPMNT AS SFC HI PRES WILL BE BUILDING INTO THE RGN...AND
INSPECTION OF 12Z NAM/GFS PROFILES SHOWS VERY LIMITED CAPE SO
WILL LOWER POPS TO SLGT CHC THESE AREAS FOR TUE/WED AFTN. OTRW...NICE
WX WITH SEASONABLE TEMPS AND PS DAYS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
SUBTLE FEATURES WILL INFLENCE THE WX IN THE LONG TERM AS THE SFC
RDGG BRKS DOWN EARLY IN THE PD. OPERATIONAL MODELS SHOW A WEAK FNTL
BNDRY TRYING TO DROP SOUTH FROM CANADA FRI INTO SAT BEFORE
EVENTUALLY WASHING OUT OVER THE AREA. WITH HTG...THIS MAY BE ENUF
LL CONV TO DVLP ISLTD AFTN CONV FRI AND SAT.
TEMPS WILL SHOW A GRADUAL RECOVERY THRU THE PD...RCHG ABV NRML BY
FRI AND SAT. STILL DFRNCS BETWEEN HPC GUID AND GFS GENERATED
MEX...SO BLENDED GUID WITH PRVS FCST TO CONT A SLOW UPWARD TREND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
FCST AREA CAUGHT BETWEEN A COLD FNT APRCHG THRU THE UPR LAKES AND
A WV MVG UP THE EAST CST. THIS WILL LEAD TO A GRADUAL INCRS IN
CLDS...ALTHOUGH CIGS WILL REMAIN VFR THRU AT LEAST 12Z MON. BY
THEN...CONV LL FLOW WILL DVLP SHWRS LWRG CIGS AND VSBY INTO THE
MVFR RANGE THRU THE END OF THE PD.
WITH THE APRCHG SYSTEMS SLOWING AS THEY NEAR...WINDS WILL BE
VRBL...BUT GNRLY LGT IN THE WEK GRADIENT.
OUTLOOK...
MON AFTN/TUE...SCT MVFR PSBL IN AFTN SHRA/TSRA.
WED/THU/FRI...MAINLY VFR. MRNG VLY FOG PSBL WITH IFR AT ELM.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
LONG TERM...DGM
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
246 PM CDT SUN AUG 19 2012
.SHORT TERM...THROUGH TUESDAY NIGHT
246 PM CDT SUN AUG 19 2012
SURFACE ANALYSIS THIS AFTERNOON SHOWS A WEAK COLD FRONT EXTENDING
ACROSS CENTRAL WISCONSIN INTO WESTERN MINNESOTA. HIGH PRESSURE WAS
CENTERED OVER NORTHERN NORTH DAKOTA.
LOCAL AND REGIONAL RADARS ARE SHOWING A FEW SHOWERS DEVELOPING
ALONG AND AHEAD OF THE FRONT ACROSS WISCONSIN INTO EASTERN
MINNESOTA. MU CAPES AROUND A 1000 J/KG ARE IN PLACE AHEAD OF THE
FRONT BUT WITH A WEAK WIND FIELD...THE CONVERGENCE ALONG THE FRONT
IS NOT VERY STRONG. A WEAK SHORT WAVE TROUGH WAS PROVIDING ENOUGH
LIFT TO AID THE DEVELOPMENT OF THE SHOWERS. THIS WAVE WILL SLIP
SOUTH OF THE AREA THIS EVENING TAKING THE FORCING WITH IT. SOME
CONCERN THAT ADDITIONAL WAVES UP STREAM IN THE FLOW ALOFT COULD
CONTINUE TO PROVIDE SOME WEAK FORCING THROUGH THE NIGHT.
HOWEVER...ONCE THE FRONT GOES THROUGH DEW POINTS ARE EXPECTED TO
FALL INTO THE 40S. THIS ALONG WITH THE LOSS OF HEATING...SHOULD BE
SUFFICIENT TO LOWER CAPE AND ALLOW THE SHOWERS TO DISSIPATE. WILL
CARRY A SMALL RAIN CHANCE ACROSS THE SOUTHERN HALF OF THE AREA INTO
THE EVENING TO COVER THE DISSIPATING EVENING SHOWERS.
ONCE THE SHOWERS ARE DONE...THE SKIES SHOULD CLEAR OUT AND WITH
THE HIGH BUILDING IN...THE CONCERN BECOMES WHETHER VALLEY FOG WILL
FORM. ONCE AGAIN...THIS DOES NOT LOOK TO BE A CLEAR CUT EVENT. THE
WINDS AT THE SURFACE ARE EXPECTED TO DECOUPLE AND WITH THE CLEAR
SKIES...GOOD RADIATIONAL COOLING SHOULD OCCUR. HOWEVER...THE
FORECAST SOUNDINGS FROM BOTH THE 19.12Z NAM AND 19.17Z RAP SUGGEST
THE WINDS JUST ABOVE THE SURFACE UP THROUGH AT LEAST 5K FEET
SHOULD BE AROUND 10 KNOTS...BUT DECREASING TOWARD 12Z MONDAY.
ALSO...THE NAM SUGGESTS THAT SATURATION SHOULD ONLY OCCUR AT THE
SURFACE WITH DRIER AIR ABOVE WITH THE STRONGER WINDS. WOULD EXPECT
SOME FOG TO BE AROUND BUT WOULD NOT EXPECT THE WHOLE VALLEY TO
FILL IN AND WILL MAINTAIN THE MENTION OF AREAS OF VALLEY FOG. THE
HIGH WILL THEN DRIFT SOUTHEAST ACROSS THE AREA AND PROVIDE QUIET
WEATHER INTO TUESDAY NIGHT.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
246 PM CDT SUN AUG 19 2012
MODELS IN THIS TIME FRAME HAVE BEEN SHOWING SOME INCONSISTENCIES
ON HOW THE PATTERN WILL EVOLVE AS ENERGY COMES OUT OF THE MEAN
LONG WAVE TROUGH ALONG THE WEST COAST. THE LATEST MODELS RUNS
STILL SHOW A SHORT WAVE TROUGH COMING OUT OF THE WEST COAST SYSTEM
STARTING WEDNESDAY. HOWEVER...NOW INSTEAD OF BUILDING INTO THE
UPPER MIDWEST...THE UPPER LEVEL LOW MOVES NORTHEAST TOWARD CENTRAL
CANADA BRINGING THE SHORT WAVE TROUGH THROUGH THE AREA WITH A
POSITIVE TILT THURSDAY NIGHT THROUGH FRIDAY NIGHT. AS THIS IS
HAPPENING...THE UPPER LEVEL THAT HAD BEEN OFF THE WEST COAST IS
SHOWN TO START MOVING EAST ACROSS SOUTHERN CANADA IMPACTING THE
UPPER MIDWEST OVER THE WEEKEND. AT THE SURFACE...THE 19.12Z GFS
REMAINS STRONGER WITH THE LEAD SYSTEM THAN THE 19.00Z ECMWF
SHOWING A LOW ALONG THE CANADIAN BORDER WITH A COLD FRONT COMING
INTO THE AREA. MEANWHILE...THE ECMWF CONTINUES TO JUST SHOW A WEAK
SURFACE LOW DRIFTING ACROSS THE UPPER MIDWEST. BOTH MODELS THEN
SHOW A LOW MOVING ACROSS CANADA WITH ANOTHER COLD FRONT OVER THE
UPPER MIDWEST WITH THE MAIN UPPER LEVEL LOW...BUT DIFFER ON THE
TIMING WITH THE GFS BEING THE QUICKEST. IN GENERAL...WILL CARRY 30
TO 40 PERCENT RAIN CHANCES STARTING THURSDAY NIGHT THROUGH THE
WEEKEND AND WAIT FOR LATER MODEL RUNS AND HOPEFULLY BETTER
AGREEMENT TO MAKE REFINEMENTS.
&&
.AVIATION...THROUGH 18Z MONDAY
1242 PM CDT SUN AUG 19 2012
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS NORTHEAST
IOWA AND SOUTHWEST WISCONSIN THIS AFTERNOON. A FEW OF THESE MAY
DEVELOP AS FAR NORTH AS THE INTERSTATE 90 CORRIDOR. HOWEVER THE
CONFIDENCE IS NOT HIGH ENOUGH TO BE INCLUDED IN THE TAFS.
FOR TONIGHT...SKIES WILL BE CLEAR ACROSS THE REGION. HOWEVER THE
WINDS JUST ABOVE THE BOUNDARY LAYER REMAINS IN THE 10 TO 15 KNOT
RANGE AND DRIER AIR IS BEING ADVECTED INTO THE REGION. AS A
RESULT...THINKING THAT THERE WILL BE SOME AREAS OF VALLEY FOG JUST
NOT SURE WHETHER IT WILL ACTUALLY AFFECT KLSE. AS A RESULT...KEPT
THE BCFG GOING IN THE TAF. AS FAR KRST...IT LOOKS LIKE THE DRIER
AIR WILL WIN OUT...SO REMOVED THE 4SM BR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
246 PM CDT SUN AUG 19 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...BOYNE